I was excited to see the announcement of the relabeling of clopidogrel (a.k.a. Plavix) by the FDA. The FDA exerts much of its influence on drug companies and medical practitioners by approving the “label” that describes the uses, doses, cautions, and much other information about using a medication. It is the folded up piece of paper that is always inserted into your medication packaging (thus it is also known as the “package insert”), that then unfolds into a huge poster-sized document with tiny font and lots of information. It is a legal document which specifies what the drug company can claim about the drug, and how physicians are supposed to use it (give or take some “off label” uses, but that is another topic). I’m sure it is the star of many lawsuits.
In any case, there has been accumulating evidence that certain genetics variants of CYP2C19 that reduce its activity are associated with differential success of clopidogrel at preventing myocardial infarctions (heart attacks). Also, drugs that inhibit CYP2C19 also reduce the effectiveness of clopidogrel. Thus, the FDA modified the label for clopidogrel and warned about concomitant use of medications that interact with CYP2C19 and also mentioned that the genetic variants present in a patient may warrant careful assessment of whether to use the drug, and how much to use. This is another success for pharmacogenetics!
The pharmacogenetics database we are developing, PharmGKB, is focused on gathering evidence for the role of genetics in drug response. PharmGKB staff have a good working relationship with some FDA scientists, and we are all very interested in finding out about other drugs for which there is mounting emerging evidence that genetics may play an important role. In some cases, the FDA may even launch a process to determine if the label should be modified in light of new evidence. If you come across compelling scientific evidence for genetic determinants of drug response, let us know at firstname.lastname@example.org. We will gather together responses and assess them on a regular basis–we will even alert our friends at the FDA to those that are reaching a critical point!
You can see a list of drugs with specific FDA language about genetics on PharmGKB.