ADHD Rx Pharmacokinetics & Pharmacodynamics — Pt. 4

Genetic testing for ADHD medications Part 4 pharmacogenetics pharmacokinetics

In this post we talk about two things in the context of ADHD gene-testing, Pharmacokinetics and Pharmacodynamics. Two very technical-sounding words. But don’t worry, we break it down for you.

Welcome to the next post in my 7-part series: Genetic Testing for Choosing ADHD Medications. In this serieswe address this question:  What’s the best ADHD medication? Simple answer:  The medication that works best for the individual.

Don’t you hate that? Are there any easy answers when it comes to ADHD?  If you’ve found some, drop me a note below. I’d love to know.

Trouble is, ADHD affects individuals—not clones. It’s easier to market stereotypes but much harder to convey the potential complexity, individual to individual. Relying on simplistic stereotypes means missing the boat.  For example, “I can’t have ADHD. I’m always on time!” Some people with ADHD are very punctual; ADHD affects them in other ways.

It’s the same with genetic factors. There is no “ADHD gene” — or even a set of genes. Instead, this highly variable syndrome called ADHD involves potentially hundreds of genes.

No Slam Dunk

All this is why the genetic tests for ADHD medications do not provide the slam-dunk answers that many patients and doctors believe they do. Without knowing this, you risk depriving yourself or your loved one—or your patients—of  the optimal medication treatment.  Over 7 posts, we explain what you and your prescribers need to know.

But, yes, genetic testing for ADHD medications can provide some useful information. Specifically, you can learn more about how your genes affect your medication response—and how medications respond to you!  This gets technical. We’ll take it bit-by-bit.  If I can understand it, you can, too!

This ADHD Genetic Testing Blog Series

My scientist husband (“Dr. Goat”) and  I pooled our neurons to bring you this series. The goal: more accurate information for the layperson (and medical professionals) with little background in molecular biology or genetics.

Our collaboration required much tedious editing and back-and-forth. My twofold goal with all my books and blog posts: accuracy, clarity, and practical application.

By the way: Ten years ago, no one could have imagined Dr. Goat and me working together so harmoniously on a project. Instead, picture miscommunications galore, chronic conflict, tempers raising the roof, and few epithets tossed around before we both said, “I give up! You’re impossible!”

Thank goodness, we are past those days. Working together is fun and productive. The fact that we can now team up to produce information designed to elevate the lives of our readers? Doubly rewarding.

Note: This post is a little longer than the previous ones. We thought it best, however, not to break up the concepts. So, settle back, take it slowly, and enjoy! This is fascinating stuff, with applications that extend beyond ADHD medications.

best adhd medication

—Gina Pera

The “Best” ADHD Medication? Wrong Question

By Dr. Goat & Gina

Dr. Goat and Gina PeraGenetic testing for ADHD medications offers one clear benefit: It can help to identify whether you metabolize medications slowly, normally, or very quickly.  That’s the focus of this post.

Now, what is the first very important point to understand about medications? That’s right: Dosing matters. Assuming that the diagnosis is correct and the medications being considered are recommended for it, beneficial effects depend upon identifying the dosage that works best for the individual.

Too low a dose? You don’t get a therapeutic benefit (nothing happens).

Too high? You might start encountering unacceptable side effects—despite that medication being an excellent choice for you.

So, just like Goldilocks, it is crucial to reach a “sweet spot” of dosage. In that sweet spot, you will get the full benefit of the drug with minimal side effects. [Gina does an excellent job of explaining this vis a vis ADHD medications in her first book, Is It You, Me, or Adult A.D.D.?]

Gene Variants Dictate Drug Response

One factor to consider when aiming for that sweet spot of medication effectiveness: how your specific gene variants affect drug response.

We discussed “gene variants”  in Defining genotyping, or genetic testing

To recap: Genetic variation (or variants, sometimes called mutations) describe the tiny variations in the DNA sequence in each of our genomes. Genetic variation is what makes us all unique—of hair color, skin color, height, or even the shape of our faces. (Learn more at Genomics 101: What is a variant?)

That’s where genetic tests come in. They identify these gene variants—that is, variations on a common gene. In turn, this information helps you to:

  1. Determine what dosage you should start with, and
  2. Decide the order in which drugs should be evaluated.

This information can be especially valuable if you are

  1. Beginning drug treatment for ADHD,
  2. Considering changing to a different drug, or
  3. Introducing an additional drug to your regimen.

It’s worth re-emphasizing: Genetic testing for ADHD medications will not be a “silver bullet.” It is simply a starting point. The last post in this series will examine how I might use my personal results.

best adhd medication

Pharmacokinetics (PK) and Pharmacodynamics (PD)

If we want to learn more about how our genes affect ADHD drug response, we need to talk about pharmacogenetics.

Briefly defined, pharmacogenetics is the study of genetic variations that can influence individual responses to pharmaceuticals. Pharma. Genetics.

An earlier post gave an overview of pharmacogenetics. Now we go into more detail on two key aspects:

  1.  Pharmacokinetics (PK): “What the Body Does to the Medication”
  2.  Pharmacodynamics: “What the Medication Does to the Body”
adhd Pharmacokinetics Pharmacodynamics
Bi-directional influences on medication response: Pharmacodynamics (“What the medication does to the body”) and Pharmacokinetics (“What the body does to the medication”)


1. Pharmacokinetics (PK): “What the Body Does to the Medication”

We’ve all seen those TV commercials for laundry stain-removers with enzymes. These “scrubbing” enzymes find their targeted stains, latch on, and break down the stain.

Guess what? We also have enzymes in our bodies—but not to break down stains. Instead, our enzymes break down certain substances and convert them into other substances. For example, stomach enzymes break down the food you ingest into tiny bits that can be converted into energy.

Among their many functions, enzymes convert inactive drugs into the active form. Once that conversion happens—and only after it happens—we can actually benefit from the medicine.

(We’ll explain examples of an active and inactive ADHD medication below.)

genetic testing

Enzymes are produced by—you guessed it!—our genes. Genes are the “instruction manuals of life.” As such, they specify how to make proteins. Proteins include enzymes and various other molecules. (To learn more, visit “How Genes Work.”)

The small variations in the instructions coded in our genes end up influencing how enzymes are produced and how they operate. In turn, some of these enzymes (and other types of proteins) affect your body’s response to a medication.

Tiny differences in your genes—and thus your enzymes and other proteins—can affect how your body can metabolize (convert) a drug. This also can affect how long the drug stays your body.

In other words, these genetic variants affect pharmacokinetics (PK).

Deconstructing this word’s Greek roots, we have pharmaco (medication) and kinetics (moving, putting in motion).

Think of pharmacokinetics as the physiological mechanisms by which the body absorbs, distributes, metabolizes, and removes a drug from the body.

CYP2D6 enzyme and ADHD medication
A rendering of the CYP2D6 enzyme

A Major Player Among Drug-Response Genes: CYP2D6

We humans have lots of enzymes., but here’s a particularly significant one when it comes to drug-response: Cytochrome P450 2D6, an enzyme encoded by the CYP2D6 gene. It breaks down about a quarter of all drugs, including:

  • Antidepressants such as Prozac
  • Breast Cancer (Tamoxifen)
  • Antipsychotics (e.g. Risperdal, Abilify,)
  • Antihypertensives
  • Pain Killers (e.g. Codeine)

Guide ADHD Medication Dosage with Genetic Testing?

One Size Does Not Fit All

You’ve probably heard people say, “I’m very sensitive to medication.”

What they typically mean is: anything larger than a very small dose knocks them for a loop. By contrast, there are the “nothing phases me” types— and of course plenty of people in between. This in part due to their drug-response gene variants.

For example, there are generally three categories that describe the rate at which humans metabolize drugs, based on the enzymes produced by their gene variants:

  1. Slow, or poor, metabolizers: These folks don’t break down medications well at all. Their genetic differences make them slower than average at converting the drug.
  2. Extensive, or normal, metabolizers: These folks metabolize drugs normally. This is the most common class, representing the type of people for which most drugs are designed.
  3. Rapid metabolizers: This is the opposite extreme to slow metabolizers. These people may require a higher-than-average dose of a medication.

Sometimes these categories are further broken down into smaller gradients, such as ultra-rapid metabolizers and intermediate metabolizers.

adhd Pharmacokinetics Pharmacodynamics metabolizing
Where are you in the metabolizer spectrum?

Why Does Metabolizer-Type Matter?

Why is it important to know what type of metabolizer you are? If your body metabolizes a drug too quickly, it can decrease the drug’s efficacy. At the other extreme, if your body metabolizes the drug too slowly, unacceptable side effects may result.

Knowledge is power. If you know that you are a slow metabolizer, you can insist on being started at a lower-than-average dosage. That way, you’ll get a better idea if the drug is a good choice for you—rather than stopping it prematurely due to a too-high dose.

(You don’t absolutely need genetic testing for this purpose, though. Instead, you can follow the wise practice of “start low, titrate slow.” That is, increase the dose slowly.)

Two Types of Drugs: Inactive and Active

Yes, let’s throw in another factor in medication response: whether the drug is inactive or active

Typically, a drug is taken in its active form; it goes to work “as is.” Think of it as the protein equivalent of “ready to wear”.

Other drugs, however, enter the body in an inactive form and require some additional … alterations. These drugs rely on bodily organs such as the liver for conversion to the active form in order to take effect.  Genetic variants play a role here, too!

1. An Inactive Form of ADHD Medication: Vyvanse

Consider the ADHD medication Vyvanse. It starts out in an inactive state.

For this reason, it has been marketed as being less easily abused than other medications in the amphetamine class of stimulants (e.g., Adderall, Dexedrine).

The medication in the Vyvanse capsule becomes active only when it reaches a certain point in the gut. At that point, specific gut enzymes convert it into the active form of the drug (lisdexamfetamine). Inactive medications are also called “pro-drugs.”

inactive and active drugs
PRO DRUGS are the inactive forms of drugs, which require conversion by the body to be effective. ACTIVE drugs arrive in the body “ready to go.” Vyvanse is an example of an ADHD medication that is a pro-drug, or inactive form of the medication.

2. An Active Type of ADHD Medication: Strattera

Now let’s consider an ADHD medication in its active form: Strattera. This non-stimulant was the first drug to receive an FDA-certified indication for adult ADHD.

Below is an excerpt from the drug label for Strattera regarding genes that affect its metabolism. By the way, this is FDA-controlled text. That means it is carefully validated and evidence-backed.

Note in the text the aforementioned CYP2D6. This gene influences the metabolism of many drugs in addition to Strattera and is known to have many variants:

CYP2D6 metabolism — Poor metabolizers (PMs) of CYP2D6 [-metabolized drugs] have a 10-fold higher AUC and a 5-fold higher peak concentration to a given dose of STRATTERA compared with extensive metabolizers (EMs). Approximately 7% of a Caucasian population are PMs. (…) The higher blood levels in PMs lead to a higher rate of some adverse effects of STRATTERA (see ADVERSE REACTIONS).

Layperson’s Translation

Poor metabolizers of Strattera reach a much higher peak blood concentration (5 times higher) than extensive metabolizers. Therefore, they are more likely to manifest “adverse reactions” (side effects). These range from constipation to dizziness, as stated in the drug label.

If you are Caucasian, your chances of having the poor metabolizer form of CYP2D6 are pretty high (7%). The drug label says nothing about other racial groups, but that doesn’t mean these groups don’t have poor metabolizers. It may simply mean there is no data available for them, or the data are simply not listed here.

As you can see, it is very useful to know which variant of a gene you have, whatever the type of drug (active or inactive). This is especially true for CYP2D6 because it metabolizes a huge number of drugs.

Conversely, some drugs are metabolized by only very few genes. So in practice, drug-response genotyping typically involves several genes so as to get the whole picture. (In Part 2 of this series, we list the four genes involved in the genotyping tests we took for ADHD medications: CYP2B6, CYP2D6, ADRA2A, and COMT.)

genotype-specific dosages

Two Scenarios for Slow (Poor) Metabolizers

If you are a poor metabolizer, there are two very different scenarios to consider. Each scenario rests on whether the drug in the bottle is 1) active (ready to go) or 2) inactive (the body must metabolize it into an active form):

1. If the drug is taken in its active form, the poor metabolizer might require a lower-than-average dosage.

If you are a poor metabolizer, you are slower at removing the drug from the bloodstream than the average person. As a result, you could reach a blood concentration that is too high even if given an “average” dose. That potentially triggers side effects.

The outstanding question then becomes: how much lower of a dose should you take? Unfortunately, there is no ready answer to that question (more below).

2. If the drug is taken in its inactive form—that is, the drug must be metabolized to become active—a standard dose might not be enough.

What?! How can that be?

We just said poor metabolizers risk having too much medication in their system, even with an average dose. How is it that poor metabolizers now suddenly do not get enough from an average dose?

Here’s why. If you’re a poor metabolizer, you are slow at converting the inactive drug into its active form. Therefore, you are failing to reach the dose necessary for beneficial effects, and the drug gets cleared from your system before having had a chance to be converted.

To recap, the slow metabolizer risks two primary effects:

  1. An over-concentration of active medication
  2. An under-concentration of inactive medication

2. Pharmacodynamics: “What the Medication Does to the Body”

Again, pharmacodynamics refers to the manner in which the drug affects a cell. Pharmacodynamics is all about how the drug does its work.

For example, consider the “lock and key” nature of the way a drug typically works with a cell. The “lock” is the receptor, a structure on the cell’s surface that selectively receives and binds a specific substance.  (Like enzymes, receptors are proteins made according to genetic instructions.)

In this illustration, Drug A fits the receptor perfectly. Drug B doesn’t come close. Substance A can bind to the receptor and an action results.

adhd Pharmacokinetics Pharmacodynamics

A stimulant such as Adderall or Ritalin interacts with certain receptors with great specificity. That is, it interacts only with those receptors.

This lock-and-key” interaction is imperative for the drug to do its job. By interaction, we mean that Adderall molecules literally slot into those specific receptors in the same way as, well….as your Big Gulp fits snugly in your car’s cup holder.

The snugness of the stimulant with its receptor, however, can vary. Much depends on—yes, that’s right— the variant of the gene that produces this receptor.

Some forms of the gene will produce a receptor with good snugness. That means less stimulant is required to reach a given effect.

Yet, other variants may produce a receptor form with more … looseness. That requires piling more drug (higher dosage) into the “cup holder” to reach the same snug-fitting effect.

Gene Testing to Inform ADHD Drug Therapy

Your Comments and Questions Welcome

  • Are you with us so far?
  • Are you gaining a better idea of how genes can affect ADHD drug response? 
  • Do you see how the simple three-column listing of medications in genetic testing barely skims the surface—and can sometimes steer you away from medications that would work very well for you?
  • Have we begun to make it clear: There is no best medication for ADHD—only the medication that works best for you, at the appropriate dose.
  • With the last post (7), we’ll provide a list of takeaway points.

Coming up next: ADHD Gene-Testing Benefits and Limitations

All 7 Posts in this Series:


1. Explains genetic testing as it relates to ADHD medication-response

Genetic Testing for ADHD Medications: Overview

2. Dr.  Goat and I share our ADHD genetic test results—and reactions

Gina & Dr. Goat Share Our ADHD Genetic Test Results

3. Defining the term genotyping, or genetic test

What Is Genetic Testing for ADHD Medications?

4. This Post: Explains how, when, and why this data might prove helpful

5. Genotyping data provides only one piece of the puzzle

ADHD Medication Gene-Testing Benefits and Limitations

6. A closer look at Gina’s ADHD genetic testing results

Gina’s Gene-Testing Results

7. Drilling down into Dr. Goat’s Results — to explain more about the data

Dr. Goat’s ADHD Genetic Test Results—A Closer Look

We welcome your comments.


—Gina Pera and Dr. Goat




53 thoughts on “ADHD Rx Pharmacokinetics & Pharmacodynamics — Pt. 4”

  1. Thank you for your article.
    I am prescribed Vyavanse 40mg. The extended release that lasts 14 hours.
    My Dr is pushing back on increasing my dosage. I took 70mg one day and it worked beautifully.
    Can you tell me what the average dose of Vyvanse is being used? If more people are taking a higher dose, then I can use this to persuade.
    Or, are you noticing a typical treatment with the extended release and a fast acting as needed?
    I am planning on the genetic testing, however I really want to get him to increase my dosage sooner then I can get my testing done.

    1. Hi Tamara,

      A few points:

      1. Vyvanse doesn’t last 14 hours for most people. That’s just marketing — and unfortunately too few MDs question the marketing.

      2. What does it mean to “work beautifully?” Your MD might be concerned that you are going for the euphoria and the “push” — rather than using medication to create more balance in your life, creating routines, etc..

      3. We can’t really talk about average doses with Vyvanse — because there are no average people. 🙂

      4. Most people and their MDs are not properly targeting goals for ADHD treatment. They are simply winging it. Not a good practice.

      You can learn more about what MDs should be telling patients in my course on ADHD sleep and medication. It’s actually on a Black Friday sale today. Use the code BLACKFRIDAY for 50% off.


  2. Hi! I have a question. Would vyvanse be something that would even work if I rapidly metabolize? Right now my adderall instants only last one hour in and out of my system. It’s insane.

    I really do not want to be on Adderall anymore. And honestly would love to and have tried my hardest to find a natural approach. But nothing seems to help me enough although of course my cleaner eating and way of life along with supplements and aminos etc are better for and helping heal my body, overall I still just feel so debilitated at times and just am struggling to function and focus.

    But I don’t know what other medication or alternatives to try that will even help me if even adderall, at higher and more frequent doses is in and out of my system so quickly.

    And if my gut health isn’t great to start with would an inactive like vyvanse even uptake? I know I don’t understand all of this, I just really need some advice and direction. I don’t know what to do and I’m really struggling.

    1. HI Erica,

      There could be many reasons other than “rapid metabolism” for Adderall lasting only an hour for you.

      You really can’t know if Vyvanse will work better for you until you try. It’s as simple as that.

      I wouldn’t get bogged down in trying to understand what gut health might have to do with Vyvanse absorption……just try it. 🙂

      I know many people who did well on Adderall who do better on Vyvanse — and many people who did poorly on Adderall who do well on Vyvanse.

      By the way, if you haven’t tried a methylphenidate stimulant, you don’t know if that might work better, too.

      good luck!


  3. kalina miller

    Help! I just got a genetic test done and discovered I am an ultra rapid metabolizer for cyp2D6. My NP refuses to give me an adequate dose and it affecting my way of life. How can I convince her that I need a higher than normal dose without sounding like I am drug seeking?

    1. Hi Kalina,

      Who ordered the genetic testing? Why isn’t that person doing your prescribing? That’s typically the way it goes.

      Are you trying to get a higher dose of Adderall? That itself could be the problem.

      You want to be sure that you’re taking the medication properly. That you’re getting enough sleep, eating well, and implementing supportive strategies — not depending on the medication to “propel” you through the day. Unfortunately, that is how many people use Adderall.

      If that’s not the case, it might be that you need to find another prescriber.

      Some NPs do well. But typically it requires specialized training.


  4. Hi Gina,
    Help! I’ve been on and off various medications for ADHD for the last 11 years (I’m 31) and while they’ve all helped with my ADHD to varrying degrees, they all seem to cause early waking/waking insomnia. I eat healthy, work out 4 times a week, and when I’m not on a medication, I sleep all the way through the night, even if I fail to keep a consistent nighttime routine or good “sleep hygiene”. When I’m on medication, even the lowest doses taken first thing in the morning, paying lots of attention to having good sleep hygiene, I start to consistently wake up after about 4-5 hours of sleep and can’t fall back asleep till 2-3 hours later… it’s a bad time 🙁 To be clear, I have no issue falling asleep – especially as I become more and more sleep deprived, I just can’t stay asleep for some reason.

    I recently heard about non-stimulant medications (like Strattera) and thought I’d finally found an answer, but after reading this blog and Strattera’s side effects, I think I’m a poor metabolizer accross the board and will likely have insomnia on any ADHD medication. Do you know of any medications/methods or other research into increasing enzyme produciton so that medications can be broken down more quickly?

    To provide some more detail on my experience:
    I’ve tried Concerta and Vivyance in the past, short-release 5mg (split in half!) Adderal, and I’m currently on 5mg Ritalin. These extremely low dosages don’t actually help the ADHD as much as I’d like, but they are still enough to cause the waking insomnia – sometimes even a day or 2 after I take them. I take it first thing in the morning around 7:30am. I consume no more than 135mg of caffiene, all before 10am (v8 + Energy, MUD/WTR, and sometimes a kombucha) (I tried doing 0 caffiene for a month in the past with the 5mg Adderal, but that just left me less focused and still having waking insomnia… but I’d be willing to try no caffeine again. When not on ADHD medication, the caffeine only causes me issues if I have a lot more than normal or drink it after 2pm). I regularly go to bed at 11pm, I have orange UV filtering glasses (ones that even block periferal light), I make sure not to eat or drink anything or even look at screens past 9pm (none of this really seems to make a difference, it’s mostly a big inconvenience). After a lot of trial and error, I’ve found that taking 10mg CBD+3mg melatonin gummy, 250mg chelated magnesium (from magnesium oxide, amino acide chelate), and 200mg L-Theanine around an hour before bed does seem to help me get closer to 6.5 hours of better quality (less tossing/turning) sleep, but still very short of the 8.5 hours I’d be getting without medication.

    If you have any suggestions at all for me to look into, I’d be super grateful! I’m worried I may never find a medication that doesn’t force me to choose between being able to sleep or being able to focus.

    1. Hi Zach,

      Wow, you’re really diligent about all this. How frustrating to not get the benefit you’re seeking!

      Here’s the thing: Most adults with ADHD that I know do best with a second medication, in addition to a stimulant — typically something targeting serotonin/norepinephrine.

      It might be that there is a co-existing depression/anxiety issue. By that I mean, not “fallout” from ADHD that makes a person “depressed” and “anxious”. But actual, gene/neurotransmitter-based depression and anxiety.

      Sometimes, though, this situation is actually caused by the stimulant. To put it simply, it can put downward pressure on serotonin in parts of the brain, and that can adversely affect sleep.

      That doesn’t mean, for many people, stopping the stimulant. It means adding an SSRI or maybe a low dose of Strattera (e.g. 25-40 mg, maybe taken in the late afternoon, to help with sleep).

      The medical experts I respect say that Concerta and Strattera (again, at a lower dose) often work very well together that way.

      An added benefit is that when the stimulant wears off, Strattera tends to provide a little softer landing — and some degree of symptom mitigation.

      In my experience, there’s a little more difficulty in balancing the potential anxiety-inducing effects from the amphetamines (Vyvanse, Adderall, etc.). But not impossible.

      Also: Even though you are able to sleep okay when NOT taking a stimulant and taking caffeine, that doesn’t mean that taking caffeine when you are also taking a stimulant won’t be “too much.”

      You might try eliminating the MUD/WTR for a while, if you try the stimulant again. That’s a lot of uncontrolled herbs and “adaptogens”. Despite the claims, we really don’t have a clue about the contents and potencies.

      re: nighttime supplements:

      —I would not rely on any type of CBD, not while you are still trying to dial in ADHD medications.
      —3 mg melatonin ….that’s a fairly high dose, if accurate (meaning, the claim)
      —You might try additional magnesium, earlier in the evening, or a different chlelate
      —L-Theanine might be helpful but if we’re talking about a “serotonin situation” caused by the stimulant, it might be best to try a 5-HTP product.

      These are just my personal opinions. I hope you find something useful! 🙂


  5. First and foremost, I just have to express my gratitude for your blog. You are profoundly helpful to SO many. This specific blog post was extraordinary detailed and easy to comprehend. THANK-YOU!
    -Started ADHD meds 6ish months ago. Addy was Horrible.
    I then tried Concerta 54 mg. Worked fine… then after a month I randomly had severe anxiety and crashes. I dropped to 36mg Concerta.
    NOW 36mg is too much. Feeling sad with my crashes now, first time ever. 36mg isn’t even that much? Now I have to drop it? ugh.
    I experimented with some 5mg Ritalin IR boosters and discovered that 7mg is my sweet spot, and 5mg after every 2 hours or so.
    how odd right? not only does it seem I need a baby dose of Ritalin, but it also only lasts 1-2 hours max? I’m in a fun situation. I found something that works great, but only for such a short time.
    Funny thing is that I discovered I had ADHD by taking Sudafed for a stuffy nose. I felt the best I’ve ever felt. I was calm, no anxiety and motivated to work. Frankly, the decongestant was debatably better. It was so nice, I felt carefree and relaxed. I hear decongestant works on norepinephrine, but Ritalin does too? ugh.

    (I blame my reduction in tolerance to high caffeine intake potentially crossing over, so when I dropped my caffeine, my methylphenidate went down also.)

    1. Hi JW,

      Thanks for letting us know you like this series. It was a lot of work! 🙂

      Funny you mention Sudafed. That’s pretty much how I open the medication section in my first book. (I’ll link to it below.)

      Here’s the thing…..why did your prescriber start you at 54 mg Concerta. That’s …….not recommended. (Had to restrain myself there).

      It’s vital to “start low, titrate slow(ly).” Otherwise, you will never know if the Rx wasn’t right for you or if the dosage was too high.

      Is it brand/authorized-generic Concerta?

      Read this:

      Yes, IR Ritalin doesn’t last long for most people. Hence the Ritalin Roller Coaster.

      Sorry but I cannot compare Sudafed to Ritalin in any meaningfully scientific way. 🙂

      But to semi-answer your question, Strattera (atomoxetine) targets norepinephrine.

      Yes, it’s tricky to gauge how a medication is working when caffeine or nicotine is being consumed. Too many synergistic (and typically not in a good way) effects.

      Also, the “crash” might in fact be that the Concerta is wearing off, and you’re better able to notice the transition to baseline symptoms.

      Most people I know do best with a second dose in the afternoon (presuming it’s taken early in the morning…. 7-8 am). Sometimes a little lower dose.

      Check my book for a basic protocol….the ones prescribers are supposed to know….. You can just start with those chapters and swing around to the rest later.

      I hope this helps!

      take care,

  6. Thank you for the answer, and also for this informative serie of posts! It has helped me in so many ways!

    I have tried the MPH medication before, and it was “draining” from me very fast, and I needed to have more of the dosages (54mg + 36mg) and still I had the very big crash in the early afternoon, and when taking the extra dosages I felt the side effects rising with it, I had no appetite at all and in the evenings I was so tired but could not sleep and tried to get the dopamines up by eating sugar (candy, chocolate, creasy stuff loads..). Also my heart rate was high, even tho my BP stayed normal. Also I did notice that MPH made my hormonal changes like never before, they worsened them so bad. Vs. Vyvanse just stops working as well, which way more tolerable. I have that every time my estrogen drops so during ovulation and when menstruating.

    I do sleep enough, I think, but I do need it a lot(8-10h) and nowadays I even think, that I’m more tired the more I sleep? And I do take the vitamins, but I should now start to take also some electrolytes since I’m drinking water way more than before.. it’s on the list, will do that ASAP.

    Now that you said it, it may just be the “normal” that’s coming back, since it’s not that big of a crash than what I had with MPH!

    When you said I could try to take another dose of Vyvanse, should I divide the 70mg, or could I even think that I would take more in the afternoon? If this Dexedrine won’t work, I will discuss that with my doctor! Good point. I have had it only once a day, and I don’t think my doctor has never suggested otherwise.

    And I have noticed a very big difference in work days and day offs, so that’s solidly from the fact that day off don’t have any structure.. and that is hard, I feel like sometimes day offs are even harder for me mentally!

    It’s so hard, having the adhd and having that diagnosed at age 30, and now having the battle with the meds and trying to go to therapy fixing all the traits that I have made in life. Sruggggggling!

    1. HI Tonya,

      I can only imagine how difficult it is. But I also have “data” from MANY people with ADHD and their partners over the years. Especially since COVID. It’s why I still do this work — and have developed my online training. The mental health profession is just not stepping up with evidence-based ADHD treatment. And frankly, I’m sick of it. 🙂

      Yes, days off CAN be harder. If there’s no routine already established, your brain has to sort it all. Then do it all. Exhausting.

      re: dividing the Vyvanse dose.

      Generally speaking, no.

      You want to identify the dose that works best for you, while it’s in your system. So, let’s say you’ve determined that to be 70 mg. You figure out when that’s wearing off — and then add a second dosage, perhaps 70 mg again, perhaps a little lower. It just depends.

      Vyvanse is basically dexedrine. Same active chemical, but in a “pro-drug” delivery system. Often the delivery system makes all the difference — because it affects the rate at which the medication is released. If you’re taking a generic Dex (the only kind, I think, these days), that introduces its own variabilities.

      Also: hormones. Dr. Patricia Quinn has often suggested a little higher dose during the “low estrogen” times.

      Watch the water intake. This 8 glasses a day thing was made up…somewhere. Based on marketing, not science.

      Check out this essay in my “You Me ADHD” Book Club series. It’s to illustrate a point about “denial”. When the author’s uncle started drinking too much water, all sorts of weirdness ensued. 🙂

      take care,

  7. Hi Gina and Dr.Goat!

    Im having a little problems with my medication and the farmacogenes! I’m overall IM metaboliser in almost all other CYPs, but my CYP2D6 is “ultra rapid”. I’m currently on Elvanse/Vyvanse 70mg, and just now added some dexsedribe 5mg mornings and afternoons. What would you suggest to try, if this won’t work. Vyvanse lasts about 6h tops and dexsedrine just makes me sleepy, not the same way as it is without it(crash from Vyvanse), but sleepy in a more soothing calming way. Bigger dose? Some other medication? I just would want to be more productive, but I tend to need so much time just in bed in silence after work etc.

    Thank you for the response in advance!

    1. Hi Tonya,

      I wish this weren’t so hard — on top of everything else! Sheesh.

      I also wish that we could in some way advise you, while “staying in our lane”.

      This seems beyond basic discussions on this topic of pharmacogenetics, etc..

      Sometimes we can get a little over-focused on the gene issues and miss the MANY myriad other issues that can affect medication efficacy.

      For example, if Dexedrine makes you sleepy, that makes me wonder about your sleep status. Are you getting enough? Is it regular sleep – same bedtime and awaken times?

      How about diet and nutrition? Sufficient protein — and varied types of it? (Not “HIGH PROTEIN” as is the popular myth about ADHD.)

      How about vitamins and minerals?

      Right now I am working on Course 2 of my online courses. All about sleep and medication.

      Without sufficient minerals (potassium, chloride, magnesium, etc..), neurons cannot transmit messages efficiently.

      The other thing is, amphetamines do “push” out neurotransmitters from the neuron. Methylphenidates do not. Over time, I see this as a risk for depletion of those neurotransmitters, especially with a sub-optimal diet, sleep, etc..

      I imagine you have tried an MPH stimulant with poor results.

      The other thing is….medication can go only so far, as you’ve probably heard. :-). It’s important to establish structures and routines — so you don’t have to reinvent the wheel every day (takes brain power), it’s already established.

      Sorry I don’t have a straight gene-based answer for you, but I suspect the solution MIGHT lie elsewhere.

      In fact, it might even be as “simple” as a second dose of Vyvanse as the first is wearing off.

      But you say there’s a “crash from Vyvanse”. A real rebound? Or just symptoms returning as before?

      I hope this helps!

  8. Hello,

    Thanks for an interesting article! I’m happy to have found your blog.

    Do you think Bupropion could increase metabolism, which then could speed up the conversion and half-life of Vyvanse?

    I am currently trying adhd meds, and I have a “feeling” that in combination with Bupropion 300mg, maybe it gets a little too much for me. So I skipped bupropion one day and I felt better during the day and I didn’t crash as hard from the Vyvanse.

    This makes me think that if I lower my dose of Bupropion, maybe it would be worth to try Concerta again, if it could be the case that Bupropion 300mg is speeding up the half-life of the stimulants and maybe also overwhelms me so i don’t feel the positive effects as much.

    Sorry my comment is quite long and maybe a bit messy it would be interesting to hear your thoughts and opinions tho

    Best regards, Sandra

    1. Hi Sandra,

      Welcome aboard the ADHD roller coaster!

      If you think your comment is long, read other comments on my posts! :-). (I welcome long comments. There’s more details and stories!)

      I can’t comment about Bupropion increasing metabolism.

      It might be the issue is more basic — that is incompatibility. Especially for your neurochemistry.

      It’s not a scientific study, but I’ve yet to meet the person with ADHD doing well on Vyvanse (an amphetamine) and Bupropion (an atypical antidepressant that hits several targets and whose mechanism of action remains unclear). Or even with a methyhlphenidate stimulant. The result is too much anxiety.

      I cannot fathom the reason why prescribers overly fond of this “combo”. Other than being poorly informed and…not paying attention.

      And when prescribers start a patient on both at once? I’d write to the state medical board. 🙂

      I hope this helps!


    2. Doing some reading about all of this metabolic/pharmacogenetic stuff and bupropion is an inhibitor for CYP2D6
      “Half of the patients treated with high-dose BUP are converted to CYP2D6 PM [poor metabolizer] phenotype.”

      Not sure how/if that would react specifically with Vyvanse, but it could possibly be a factor. Or maybe it’s just increased dopamine or serotonin hanging around. I have similar increased stimulation with my Adderall and bupropion some days, and Adderall is an active drug, while Vyvanse is an inactive.

    3. Hi Racquel,

      I suspect that the problems with Adderall + bupropion have little to do with enzymes or active/inactive and more to do with buproprion typically increasing anxiety when taken with any stimulant, much less Adderall. That’s the stimulant with the highest side effect profile.

      So, you might want to go back to basics.

      good luck

  9. Hello again, I think I tried involving a highly complicated story in my simple question… I just wanted to know whether I have any options, stimulants wise, since I metabolize poorly in some genes but not the others.

    1. Hi Taylor,

      Of course you have options. You have the options most other people with ADHD have.

      As my husband and I explained, in enormous detail ….. TOO MUCH detail for some folks. :-). ….. these tests are mostly useless!

      Go through a logical protocol with the medication. If you don’t know what that is (and likely your prescriber won’t know, either), read the medication chapters in my first book.

      I will be covering this in Course 2 of my online training (Solving Your Adult ADHD Puzzle). Anticipated March. But Course 1 is available now, and it’s the foundation.

      take care,

  10. What an excellent post. I am considering genetic testing. My question is do we have information about the impact on extended release medication? Since Adderall XR and Vyvanse work differently for example. Where Adderall xrs extended release is based off of the stomach disolving a layer on beads.

    I can’t seem to find WHICH enzyme cleaves the lysine off of Vyvanse. I will say it seems like I’m processing the pro drug very quickly because I feel over medicated for a short time and the I crash. Nowhere close to the 14 hours they advertised.

    This is also a reason why converting from one med to another might not be wise. Like you said titration is key but some doctors want to avoid a patent being undermedicated and there are charts online for “convert Adderall to Vyvanse”. But since different enzymes are involved this might not be the right question.

    1. Hi William,

      Thank you! We worked very hard on this series!

      Yes, the fallacies that physicians and other prescribers promote — often fed to them by pharma reps, not evidence-based science — does not promote clarity on these issues. And the online mishmash of inferior information promoted as fact….makes things worse.

      It might be helpful for you to get clear on some basics.


      — The differences among the stimulant medications.

      Many people seem to think that Adderall and Vyvanse contain the same medication. They don’t. Vyvanse contains dextroamphetamine. Adderall contained mixed amphetamine salts.

      — How medication titration and selection should go

      It’s less important to know WHICH enzyme cleaves off the Vyvanse than to follow a rational protocol in selecting and titrating stimulants. AND, to be aware of other factors affecting medication efficacy (diet, sleep, caffeine, etc.)

      — Taking marketing claims with a grain of salt

      What Shire/Takeda advertises about Vyvanse and what actually happens in terms of hours of coverage….two different things. 🙂

      You might want to read the medication chapters in my first book.

      And look for Course 2 in “Solving Your Adult ADHD Puzzle” — on medication and sleep. Anticipated for late Feb. Best to take Course 1 for a strong foundation.

      I hope this helps.

  11. Gina,

    Not even the maximum doses of prescription stimulants have much of an effect on me. This includes Vyvanse, Adderall, and Nuvigil, to name a few. Even after long breaks (lasting months, even years), they have little effect. This makes dealing with ADD & narcolepsy that much more difficult. So essentially, you would say that I’m an ultra-rapid metabolizer, then? It wasn’t always like this. My stimulants used to work spectacularly, but during a year-long break from them in 2017, something major must’ve happened that totally changed my body chemistry…I resumed taking them in 2018, and for some reason, they barely helped at all. Can changes like that happen to somebody’s chemistry spontaneously? Could an OD on diphenhydramine precipitate such resistance to stimulants? Is there nothing I can do to reverse whatever happened to me?

    1. Hi Eggsy,

      I couldn’t really say about the diphenhydramine precipitate (Benadryl) creating what appears to be a resistance to stimulants.

      I could hazard some other guesses, though, as to why Vyvanse, Adderall, and Nuvigil aren’t working now for you.

      First, define “working.” What were you doing pre-2017 that you aren’t doing now—or vice-versa?

      That is, what is different now about your work, your sleep, your diet, and other factors?

      Citric acid in your diet, for example, could be having some impact:

      If you are having to self-structure your work, perhaps you didn’t build the skills and habits pre-2017 that would be helping you now?

      Many people who use Adderall, for example, use it as a “performance drug.” That is, they use it to propel them through their day with hyper-focus. This is not what treating ADHD means.

      It seems the stimulants you relied upon were Vyvanse and Adderall. The amphetamines work differently than do the methylphenidate class of stimulants (e.g. Concerta, etc.). Amphetamines do more than hold the dopamine molecule a bit longer at the synapse before it’s recycled. Amphetamines also push molecules out of the neuron.

      If your diet or your genetics mean that those molecules aren’t replenished, that means the amphetamines stop working over time. This might especially be true when insufficient amino acids are consumed…or perhaps genetic mutations inhibit uptake of certain amino acids. Amino acids are the building blocks of neurotransmitters.

      We hear this more about the amphetamines than methylphenidate. Lots more. So, there. must be a reason for that.

      You can learn more here:

      I hope this helps. Good luck.

  12. Taylor Hebert

    Hello! I’ve been dealing with many problems (mainly insane insomnia, but there’s excess sweating, anxiety, etc) for around 6 months now and found out about gene testing!

    I haven’t been able to find much on the internet, and what I have found wasn’t too informing… until I came across your website!

    Your website has been more helpful then 4 psychiatrists, and many google searches!

    I’m a little complicated though, I am a intermediate metabolizer In CYP2B6 IM 1/6, CYP2C19 IM 2/17, UGT2B15 IM 2/2, and a poor metabolize in CYP2D6 PM 4/4.

    In addition, I’m a high metabolizer in CYP3A4 1/1 CYP3A5 1/3. Also, low activity in MTHFR C677T: C/T A1298C: A/C AND decreased response in ADRA2A receptor, so methylphenidate won’t work too well.. would you be able to tell me if I have any options?

    Seems like since I’m such a bad metabolizer, I’m going to have insomnia either way. Thanks for all your help!!

    1. Hi Taylor,

      I’m glad to know you’ve found benefit in our hard work. Thanks for letting me know!

      I’m afraid your question is way above my pay grade. 🙂

      But…..can you tell me a little more?

      For example:

      1. Why do you think the insomnia is related to information you might find in gene-testing?
      2. Or, are you saying that you hope that ADHD medication treatment will help with the insomnia? (It might in part, but there are also external strategies to consider.)
      3. Why do you think that your being a “bad metabolizer” means you cannot take methylphenidate?
      4. What ADHD medications have you tried so far?
      5. So many questions. 🙂


      At any rate, I am working feverishly now to finish Course 2, Physical Strategies (sleep and medication). So, I’m something of an expert on ADHD and sleep.

    2. Hello! Sorry about the lack of background info, I figured it was way too much haha!
      1. I figured out that stimulants must be staying in my system for an extremely long time, because when taking extended releases (even in the early morning) I’m still tossing and turning all night, unable to get my brain to shut off. Since gene testing is really only good for info on metabolizing, then I figured this info would help me confirm this theory (which it did LOL).
      2. n/a, stimulants have ruined the once restful I used to get (before ADHD meds).
      3. Genomind’s report for me said specifically that methylphenidate would not be a good option, as a specific receptor for norepinephrine signaling has a “decreased response” which means I would have a “decreased response” to this drug.
      4. I’ve tried all doses of Adderall XR (all gave me bad anxiety). Vyvanse was ABSOLUTELY terrible! I tried every dose, and I was tossing and turning every 30 minutes at night, so I was basically getting maybe an hour or no REM sleep, I didn’t figure this out until I used an app to track my sleep movements. My experience with Vyvanse (given it is a very long-acting stimulant) prompted the idea that medicines are staying in my system way too long. I proceeded to try Dexedrine IR, twice a day, which was wonderful for my sleep, but horrible for my daytime tasks. The IR really only lasts around 2 hours for me and I have school in the morning and work at night, and the comedown is NOT fun! I’m trying out Dexedrine XR right now, along with 5 mg IR in the afternoon (4:30 pm, I don’t go to sleep till around 12 am) and so far so good for anxiety, and it’s slightly improved my sleep, but I still toss and turn, so it’s still not restful.
      In addition, I don’t have restless legs syndrome. Also, my sleep was perfectly fine before stimulants, and I know this isn’t related to bedtime routines or any of that because I’ve already tried everything. I’ve tried all sorts of sleeping medications, all I’ve really ever gotten out of them is morning grogginess (there goes that sloth pace metabolizing again), which sometimes went from morning to all day tiredness! Also, morning time grogginess defeats the purpose of sleep aids because I need to be able to get up in the morning and get things done, instead of skipping schoolwork or tasks and basically sleeping all day, till my work shift (3 pm), and possibly still being tired!

    3. Hi Taylor,

      There are so many variables here. From what you describe, genetic issues regarding drug metabolism are way down on the list.

      BTW, Genomind’s report absolutely cannot say that “methylphenidate would not be a good option.” No matter what it says about your receptors.

      If you’re having nighttime anxiety, I’d wager the last thing you need to be taking is any of the amphetamines.

      You might want to give MPH another try. And, if that’s not better, start investigating if you might also have an anxiety disorder (apart from ADHD-related cognitive anxiety, often mistaken for anxiety disorder).

      Also, sunlight in the morning, exercise, no caffeine, tc.

      It might be that your sleep before wasn’t “perfect” but you didn’t know it. Falling asleep quickly and easily doesn’t necessarily indicate good sleep.

      But perhaps the biggest factor here is working a late shift.

      Lots of variables.

      I’m about to record Course 2 of my online training, on sleep and medication. You might want to look for it!

      good luck!

  13. Hello ! This thread is old and I’m not sure if you guys still look at this . I’m having an issue with Adderall.I am prescribed 30mg IR twice a day . I feel nothing . I just learned about the cyp gene today and have been reading so much . Is this the reason my Adderall doesn’t work one bit ? My doc advised me to try two at once and nothing . I am so discouraged because I have severe ADHD and don’t know what to do . Is there anything that can be taken to help the cyp gene so that I am not rapidly metabolizes the medication to where it does not have an effect ? Thank you so much

    1. Hi Amanda,

      My blog is the first website on Adult ADHD. So, in that sense, it is “old.”

      Otherwise, I don’t keep outdated information posted, and I answer every comment. 🙂

      re: your question. There’s a saying regarding medical diagnosing: Think horses, not zebra.

      In your cases, you might want to examine more basic factors (horses) before you get to metabolic pathways and CYP mutations (zebras).

      Unfortunately, there are so many websites that confuse people about these issues.

      For example, if Adderall is only stimulant that you’ve tried, your prescriber needs to get up to speed.

      It might be that Adderall is just not the Rx for you. It’s not a good fit for MANY people.

      This is my most popular blog post:

      Another amphetamine stimulant choice might work better (e.g. Vyvanse) or perhaps the other class of stimulant (methylphenidate choices such as Ritalin, Concerta, etc.).

      Genetically speaking, one class of stimulant clear works better than the other for about 40% of people with ADHD.

      If it’s a generic, that might not work as well as brand.

      Are you sleep deprived, drinking caffeine, consuming cannabis? All these factors can affect how well a stimulant works for you.

      But you also need to think about what it means for the stimulant to “work.”

      Not everyone with ADHD taking a stimulant will “feel” it working. The effects might be more subtle—and not as easy to observe.

      I hope this helps.

  14. Hi, I am a psychiatric Nurse Practitioner who has a passion for treating ADHD across the lifespan.

    It is a gross understatement to say that ones ability to focus and execute in a timely fashion greatly affects one’s quality of life; including but my no means limited to how far one is able to climb academically, within ones career, and also in the successful maintenance of interpersonal relationships. I have adhd, and have always had it since I can remember; however, it wasn’t until I sustained a traumatic brain injury prior to grad school that my challenges warranted further investigation by the medical community. After all, I made the grades despite it taking me twice as long to learn materials etc.

    I am both so blessed and grateful to be where I am at today; people often look at me in disbelief when I tell them that I have had both had a TBI and have ADHD that dates back into childhood.

    Frankly though, it is my success that I am finding to be a hindrance to getting the e care that I need after my psychiatrist retired. Despite providers seeing for many many years I have had to take a higher dose of stimulant; There is still a major stigma against those of us who require higher doses of stimulant. Telling me to simply work less hours per day so my adhd medication will cover me is not acceptable.

    Yet, despite myself being in psychiatry, I continue to run into simple thinking concerning adhd treatment and what is the “max daily dose” limiting MDs comfort level in prescribing not accounting for the way in which one’s body metabolizes the medication, the length of ones work day, and how lack of focus grossly affects other areas of ones life. Please note * I have no history of addiction, none runs in my family, and have never needed early fills either. What would your recommendation be in respect to how I word this to my psychiatrist the next time that I see him, or are there any journal articles that you have stumbled upon that may be of guidance for him. THis not only negatively affects my life, but more so speaks to a microcosm of negligent care in the psychiatric setting due to personal bias and opinion void of taking into account assessment findings. numerous patients out there that do not even realize that they do have a voice.

    What are your thoughts on Geomind Testing when looking at medication metabolization of these stimulants compared to Biogeniq or Genesite?

    Lastly, do you know of any Guidelines that have been published about how fast meds are metabolized out of the body in general; and max daily doses.

    I am very impressed with the CADDRA organization; are there any such organizations in the USA that hold similar beliefs and values about ADHD care and management.

    Thank you much for your thoughtful consideration of this letter and for being an advocate for a community of patients that often struggles with having their voice heard by non-judgmental ears.

    1. Dear Amanda,

      Preach! 🙂 I am so with you!

      re: tests

      I can’t offer any useful comparisons among Geomind, Biogeniq, or Genesight.

      I’ve seen all the tests grotesquely misused by MDs who think they can interpret genetic complexity by looking at three columns.

      Funny ….. in the Adult ADHD group I facilitate, one member was going on and on last month about how great these tests are …how they take the “guesswork” out of prescribing…and how a “simple test” told him he cannot metabolize Prozac.

      Now, he’d done this before, and I tried to clarify, again, for the benefit of others: That’s not what these tests do, and they are being misused.

      Then, he kept referring to this as my “opinion” (“I know Gina has a different opinion on this.”) Repeatedly. Can you say, “Oppositional”? 🙂

      I think it makes some people very uncomfortable to know that they cannot trust their doctors on such matters and that “this lady who has written some books” might know more. 🙂

      That was our major takeaway in the series — that the most clear potential benefit from these tests would be for the rapid metabolizers who need to “prove it” to both their doctors and insurers.

      The thing is, if you rely on the test alone to convince your MD, you’re gambling that it is accurate in this regard, no matter the stimulant.

      CADDRA and maximum doses:

      Speaking of CADDRA (a fantastic organization and no, I don’t consider any other organization in North America to be on par with it), this paper includes a chart of maximum doses (there are no doubt newer papers but this is what I had time to find, just as an example). So you could begin by sharing this data with your prescriber.

      Identifying optimal dose:

      Generally speaking, the stimulant medication should “start low and titrate slow”….increasing bit by bit until side effects outweigh benefits and then ratcheting back down.

      Fears of “performance drug usage”

      Thanks to the parading psychiatry hustlers—not to mention the “self-medicators”— “Adderall abuse” is all some people know, including physicians.

      What might be more convincing to your prescriber is “data” — showing your daily routines in an effort to show you’re not using the stimulant as a performance drug. Rather, you take medication to manage your daily functioning to be commensurate with your intelligence and education.

      Just a simple chart….time to sleep/awaken, breakfast, hours of work, recreation/exercise/tasks.

      If your MD thinks you might be “too smart to have ADHD,” maybe you could share this piece from a preeminent ADHD expert, Thomas E. Brown, PhD.

      I hope this helps!
      Good luck!

  15. Hello Gina…
    I am not sure if this thread is still active, but since I had an identical question to 1-2 others I thought I’d ask it anyway. It revolves around a Poor (or Intermediate) Metabolizer of CYP2D6 and the use of Vyvanse.

    Like others, I do understand that generally speaking a Poor Metabolizer of 2D6 may need a lower dosage than the average bear of an “active” form of amphetamine, whether it be Adderall, Dexedrine or any within that family.

    The question is when using Vyvanse, an inactive Pro Drug… Does being a Poor 2D6 Metabolizer “generally” require a higher dosage to even achieve a sufficient dosing of the active form after conversion? My adult son with ADHD has at least one SNP (COMT val/val) that may require a higher than normal dosage of medication, but if his Intermediate Status on 2D6 is also hampering the conversion of his 70mg of Vyvanse to the active form that could be a fundamental reason why he constantly says he needs a higher dose and only gets about 6Hrs out of his pill.

    If there is any references showing Vyvanse uses 2D6 to convert that would be good information. Can you share any information on this or elaborate further on this topic?


    1. Dear Gary,

      I am so sorry to only now be responding to your question.

      I read it at the time, thought about it, and I have no idea. 🙂

      I sent my husband a query and failed to bird-dog it.

      I’m wondering if there might be something else going on, more “horse than zebra.”

      Is it possible that your son, like many adults with ADHD, suffers sleep deficits, over-uses electronics, has vitamin or mineral deficiencies, consumes caffeine or nicotine, and/or depends on a stimulant to “propel” him through the day rather than to provide the focus that helps to implement strategies to support Executive Functions?

      One more thought: Does he consume acidifying agents? Check out this post on how citric acid, etc. can affect stimulant performance.

      I realize that doesn’t answer your question — especially if you’re trying to document the need to your health insurance company.

      But until such time as my husband responds… (I’ll remind him).


  16. Carolina Vasquez

    Hi I have 37 years and found out just couple months ago that I have ADHD so my psychiatrist first gave me vyvanse 10 mg to start and try and after 4 hours I start feeling side effects very intense and then I felt like a rush of energy and only lasted 3 hours and then nothing else and later on in the afternoon around 4pm I was completely awake like alert and that night had insomnia and then I went up in the dose until 40 mg and I quitted the side effects were very intense and the other days I didn’t feel anything that can help adhd symptoms and you said that vyvanse and poor metabolism need a higher dose I think I’m going to try vyvanse again and this time go higher in dose after vyvanse I changed to generic adderall and I started 5mg up to 40mg in a day and nothing happened I didn’t see any changes on ADHD symptoms so I switched to generic ritalin instant release methylphenidate and I’m in 20 mg now but only lasted 1 hour and then goes away I started at 5 mg twice a day and nothing then going up until 20 mg and I thought that small dose I was going to start seeing the benefits of the drug but nothing please help me what do you think my Dr. Is also prescribing me wellbutrin but I stopped taking it because I didn’t work at all and I was taking lamotrigine too but I stopping that one too because is not doing anything
    Thanks in advance

  17. Ben Humphries

    I’m a rapid metabolizer for dexedrine, and I’ll tell you, finding a doctor who’s willing to treat me with the doses I need has been a nightmare. Finally I’ve found a competent doctor who realizes what any specialist with nine years of medical training should know, that some people are simply rapid metabolizers of certain medications. The most recent “doctor” I was on a wait list to see, told his wife, who was my GP, after receiving my medical record, awash with misdiagnoses, and failed medication attempts, that I must be suffering from “drug addiction”, never so much as having tried marijuana in my life. Of course there was no drug I had taken, except sleeping pills, that was addictive, (I did need them to sleep sometimes), but being a Canadian doctor, he didn’t know enough to understand that ADHD stimulants aren’t addictive. Hope he’s learning the basics now, but I certainly wouldn’t bet my health on it. He told his wife I was an “inappropriate referral”, and not only did I not get to see him, I had been told I had to give up my place on a waitlist, if I wanted to be put on his, after months of waiting to see another specialist. Of course there’s limited accountability in the medical profession, certainly up here, so it doesn’t matter that his abusive “diagnosis” cost me a year and a half of my life, and delayed my already severely delayed education, by that amount of time.. but, he has a medical degree, so he must be in the right. Right now I have to go back to my doctor to ask for a second dosage increase, because the vyvanse has simply never been high enough for me. I end up taking 60 mg more, then going without for six days at the end of the month, but that won’t get me through five chemistry courses this semester. What a pain. I wish I knew exactly what tests I need to take to determine what level of vyvanse and evening dexedrine IR I need. I know what dose of Vyvanse I need, about 180 mg/day + IR for the evenings, but I’d like to have it on paper, so that when my doctor retires, I’m not simply at the whim of a mental midget like the one I was wait listed to see.

    1. Hi Ben,

      I’m sorry to hear of your struggles. Canada has two excellent advocacy and professional groups: CADDAC and CADDRA. But, alas, they cannot manage the entire NHS insofar as ADHD.

      CADDRA does make available as a free download it’s excellent treatment guidelines:

      As I read, I was wondering if you’d tried Vyvanse, as it is time-release Dexedrine. Then you mention you have.

      Your doc might invite trouble by documenting your need for that dose without any independent support.

      Maybe getting the genetic test would solve a lot of problems for you. I suppose the NHS doesn’t pay for the Genesight testing. I see this company. But as with the American offerings, I do urge caution in interpreting the results. (That’s why we wrote a 7-part blog post!)

      In the meantime, have you tried strategies for reducing your need for that high dose? That is, are you using all the environmental supports to help you structure your time and focus? Calendars. Planners. Breaking up big chunks of studying into smaller ones, etc. Also, good sleep, exercise, and diet? Maybe look into amino acid precursors (e.g. L-Tyrosine).

      While not an answer in and of themselves, doubling down on these strategies might help you to maximize the dose you can get.

      I know you realize this, but I need to mention: It’s not advised to use the stimulants as “performance drugs”. In other words, your ADHD treatment should be supporting you in living a more balanced life, not tackling five chemistry courses.

      Good luck getting the help you need.

    2. Hi Dr. Pera! Thank you so much for your thoughtful response, my gosh, as I read my initial message, I sound like such an angry person. Now I’ve dropped two of the chemistry courses, so I’m sane again. I apologize for my tone in the initial message.

      I think the genetic testing could, potentially? solve some of the problem for me. At least, either way, if the results were somewhat definitive, it would put my mind to rest, and give my doctor documentation to support any “off-label” treatment, that might be necessary.

      Can I ask what lab/company you’d recommend for testing the genes implicated in vyvanse/dexedrine IR metabolism? You mentioned genesight, could that be the one to go with?

      What level of clarity could the testing give for a situation like mine, where my dosage, (130 mg), still really seems to low? I need to read the rest of your blog!

      Thanks so much,


    3. HI Ben,

      No problem. I thought you just seemed stressed. I get it!

      I already offered the name of a company in Canada doing gene-testing. Otherwise, I know none except Genesight.

      I’ve just learned that here in the U.S., the FDA is actually specifying that some medications are highly affected by metabolism. I haven’t seen the stimulants on the list of 200 or so medications already documented.


  18. Pingback: Can Foods, Acids, and Antacids Interfere with Stimulants? - ADHD Roller Coaster with Gina Pera

  19. Hi Gina,
    Your blog is very helpful and informative. I’m still slightly confused on just one point.

    You explained that a vyvanse dose would need to be raised in poor metabolizes to achieve the same effect. Were you talking about poor metabolizers of cyp2d6 or a different enzyme. I don’t mean this in a challenging way I’m just really confused because on rxlist and on vyvanses website it says lisdexamfetamine is not metabolized By cyp450 enzymes but instead it was metabolized into dextroamphetamine in red blood cells via hydrolysis.

    When I had gene testing done it showed that I was a poor metabolizer for cyp2d6 and then showed in large print”ADHD Medications metabolized by the CYP2D6 enzyme: amphetamine salts, dextroamphetamine, atomoxetine and Lisdexamfetamine” and this seems to support what you were stating in this post.

    If you could please clear this up for me I would really appreciate it because between being a poor metabolizer and being on Bupropion, which is a strong inhibitor of CYP2D6, it seems that I would not be efficiently metabolizing vyvance into its active form. Thanks so much for your time.

    1. Hi Scott,

      My husband and I are reaching the end of our vacation. We will try to answer this in a few days, but I think it’s really best if you ask your physician.

      Anecdotally, though, I haven’t seen Bupropion and Amphetamines being a great mix — too much potential for anxiety.


  20. This is such an informative article, thank you! After years of adverse drug reactions I had a physician casually remark that I must be a fast metabolizer. This gave me something to research and eventually push for some genetic testing. It had never been done at my clinic, so they were unsure what to order, but I did get 2D6 and one of the other CYP enzymes tested. Turns out I am a poor metabolizer for 2D6, which explained my adverse reactions to the Beta blockers and tricyclic antidepressants. I needed about 1/4 the dose of a “normal” person. The information obtained from the genetic testing allowed my specialist to tailor medication doses to my metabolism, allowing me to use drugs we had previously thought I could not tolerate.

    In years of researching this topic, I haven’t found such an excellent resource with so much information all in one place in layperson language. I will be sharing this article from now on when I want to introduce others to the concepts of drug metabolism and genetic testing. i feel this testing was crucial to my migraine treatment, yet my physicians were not very familiar with it. Many other patients are most likely in the same sitation, and will have to educate themselves and their doctors in order to get the help they need. Thank you again for this valuable resource!


    This is a table I find useful, that may help other readers:

    1. Hi Cristy,

      I’m thrilled that you find our (Dr. Goat and me) tedious work helpful!

      It’s said that medical-science information takes about 20 years to trickle down to the clinical level. But I knew about the CYP enzymes at least 15 years ago. How is it that some docs still don’t know? It’s a major flaw in our medical “system.”

      Thanks for all you do to educate and support healthcare consumers!


      P.S. And that’s a very helpful table. tx!

  21. Pingback: Post 7: Gene-Testing To Inform ADHD Drug Therapy - ADHD Roller Coaster with Gina Pera

    1. I am confused by the Vyvanse pharmacology too, Scott! I hope you share if you get more info. I will say that talking to my doctors has never been helpful as I am just as likely to have to explain metabolic issues to them as the other way around. However, I was able once to get sent to a clinical pharmacist who was able to at least shed some light on my genetic PM 2D6 results (which my geneticist and prescribing physician don’t understand). This was not a billable appointment as they don’t see “patients,” however maybe other patients in such confusing circumstances can see one? Otherwise, my pharmacist has been the most help (at least providing me with a table of the enzyme substrates, etc). Good luck!

    2. Great idea, Cristy. I often will refer such questions to the nearest university-hospital pharmacist. They are typically very helpful!


    3. Dear Gena,
      thank you so much for all the information you share! I’ve been diagnosed with ADHD a year ago, read your book and discovered your blog only about half of a year ago, so if my question have been answered somewhere else, please just direct me to the link. My confusion is about your two following points:

      “1. If the drug is taken in its active form, the poor metabolizer might require a lower-than-average dosage.
      2. If the drug is taken in its inactive form—that is, the drug must be metabolized to become active—a standard dose might not be enough.”

      What happened to me, is that I first was prescribed generic Adderall instant release 5 mg (blue pill with imprint cor 130), and wow!! — in about 5 minutes (!) after I took the pill everything I saw suddenly had dimensions like in childhood, I was calm and normal, stopped trying to walk into the walls instead of doorways, galloping down my food instead of chewing it, and was consistently in a good mood even after the meds stopped working. I even went to bed on time and got up as soon as I woke up, instead of lying in bed for hours in the morning like I used to. It worked! But my body could not take it: too much numbness when the meds wore off, blood vessels constricting to the point of pain, and terrible muscle pain around old injuries. So my doctor suggested Vyvanse, just 10 mg. And then it started: anger! headache and terrible eye pain! sleeplessness! We switched to brand Adderall instant release 5mg (Teva), and then that anger again (much less) with the full dose, — so I started cutting the pill down to 3/4 and still felt like I was hyperactive me again and on tons of caffeine, the latter especially when the meds wore off, doing 10 things in one day and barely sleeping. At about 1/2 of the pill I suddenly relaxed and slept right after I took it, but in the several next days the sleepiness turned into tiredness, then anxiety and feeling of indifference to anything came right after I took the dose, and feeling of being tearful, depleted, and irritated closer to the bedtime. No other meds or medical conditions were involved, so we discontinued the Adderall all together, and now I’m waiting for my pharmacy to get brand Ritalin.

      So here is my confusion: would not it make more sense, according to metabolism reaction, that I was supposed to take, and process, Vyvanse even in higher than 10 mg dose? I apologize if I misunderstood your explanations. I see your point about genetical testing, but concerned that it will confuse me even more.


    4. Hi Lena,

      Wow, that’s tough. To have such a “miracle” happen and then go away.

      There are MANY reasons to explain what you experienced.

      If you had the “angry” reaction to Vyvanse at only 10 mg, it might be unrealistic to expect better from a higher dose.

      But it will be important to give the Ritalin a trial first before going down the “metabolic” rabbit hole. 🙂


  22. Pingback: Part 6: Gene-Testing To Inform ADHD Drug Therapy - ADHD Roller Coaster with Gina Pera

  23. Pingback: Part 5: Gene-Testing to Inform ADHD Drug Therapy - ADHD Roller Coaster with Gina Pera

  24. Dr. Goat and Gina,

    This series has been great with a wealth of information on a complicated but crucial topic. Thanks for doing it!

    Just wanted to point out that ‘poor metabolism’ is a double-edged sword. There may be more side effects at standard dosages, but response rates may be higher as well. (Strattera, for example, has higher response rates in poor metabolizers than extensive metabolizers.)

    Your advice to go slow and low when trialing medications in poor metabolizers is absolutely correct, and I just want to underscore the point you’ve been making that medication selection is very complex, that there are are many factors, not just the gene profile, that have to be considered. The notion that one should “try this drug” first, next or last based on the pharmacokinetic profile is a bit of an over-reach by Harmonyx.

    When someone with ADHD has issues with substance use, OCD, anxiety, severe tics, dyslexia, insomnia, etc., we generally begin with non-stimulants regardless of whether Harmonyx says to use them first or last. In such cases, we use the pharmacogenomic profile to adjust the dosing only, not the priority.

    Thanks for indulging a nerdy comment!

    Oren Mason MD
    Attention MD
    Author — Reaching For A New Potential

    1. Hi Oren,

      Thank you so much for weighing in—and making such important points.

      We will be wrapping up with some of the issues you mention, but we figured the incremental approach would work best in explaining these complex factors.

      I, too, am most worried about the “try this first/next/last” recommendations being taken literally by patients, as I’ve already heard some parents of children with ADHD report.

      Accurate diagnosis, published data on first-line ADHD medication response rates, and the facotoring in of co-existing conditions is more important.


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