As someone who is not in the medical or pharmacy field, I am trying to look for more information as we are encountering more difficulties with Q's medication responses. So I found a site and took an online webinar and of course had to scare myself to death. They talked about a boy who took Prozac who had the same poor metabolism (PM) rating for CYP 2D6 which means that it built up to a toxic level in a few days and he died. Now, I understand why we had to switch to doing 1ml in a dropper at a time when dosing him even though he weighed around 70 lbs at the time. And why we have not been able to increase it at all. There are some medications that they said add to this problem (can further inhibit enzyme action) so you have to be careful for that (there is a genetic/DNA form and a drug induced form, Q has the genetic form). He has two systems tested as poor/reduced so that means he can have medications be toxic at a very low rate. They showed one medication....maybe it was strattera?? that could be at 25 times the dose in serum blood levels for PM's. DNA Drug Sensitivity Testing - Personalized Medicine If any of you are pharmacists or doctors or chemists who want to explain this to me in lay person terms, please feel free. I am sure I am butchering this. Bottom line, I am so glad I found this site, I printed out the drug lists which are more extensive than what I received and I was told that for Q's profile he will have some medications that can become toxic or have more adverse reactions and for others he will be able to have a lot of the medication. and it may not build up. I thought it may complicate things, did not realize it could actually kill someone. Codine is another biggie (and other anesthetic medications) ... it converts to morphine and can be built up to lethal levels and people die. For others it just wont work at all. (rapid metabolizers) . The webinar also talked about how the half life can be so altered that the medication stays in a person for an immensely longer time. There are many drugs listed and many are super common and even over the counter. Q's insurance (straight MA) covered the testing. I guess I read here many insurances dont cover it, seems like a really worthwhile investment for those who have had many strange drug responses in the past. Could save their life. Here is what I copied from the site for those who have asked: What genes are most useful to test? CYP2D6 (cytochrome P450 2D6) is the best studied of the DMEs (drug metabolizing enzymes) and acts on one quarter of all prescription drugs. Approximately ten percent of the population have a slow acting form of this enzyme and five percent a super-fast acting form. Drugs that CYP2D6 are thought to inactivate include Prozac, Zoloft, Paxil, Effexor,hydrocodone , amitriptyline, Claritin, cyclobenzaprine, Haldol, metoprolol, Rythmol, Tagamet, tamoxifen, and the over-the-counter diphenylhydramine drugs, Allegra, Dytuss and Tusstat. CYP2C9 (cytochrome P450 2C9) is the primary route of metabolism for Coumadin (warfarin), Amaryl, isoniazid, sulfa and ibuprofen. Clinical studies suggest that the use of genetic testing may be especially helpful with warfarin administration. Other drugs that are thought to be metabolized by 2C9 include, amitriptyline, Dilantin, Hyzaar, THC (tetrahydrocannabinol), naproxen and Viagra. CYP2C19 (cytochrome P450 2C19) is associated with the metabolism of carisoprodol, diazepam, Dilantin, and Prevacid. CYP1A2 (cytochrome P450 1A2) is associated with the metabolism of amitriptyline, olanzapine, haloperidol, duloxetine, propranolol, theophylline, caffeine, diazepam, chlordiazepoxide, Premarin, estrogens, tamoxifen, and cyclobenzaprine. NAT2 (N-acetyltransferase 2) is a second step drug metabolizing enzyme that acts on isoniazid, and procainamide and Azulfidine. The frequency of the NAT2 "slow acetylator" in various worldwide populations ranges from 10% to more than 90%.