Individualized therapy

is getting closer and closer. A recent study in PNAS (Proceedings of the National Academy of Science, free for all) demonstrates that polymorphisms in the gene targeted by common anti-epileptic meds carbamezapime and phenytoin and the enzyme that metabolizes the latter predict the effective dose.

The obvious implication is that one could test patients for the polymorphisms and use that to guide dosing. In the case of CYP2C9, the enzyme that metabolizes phenytoin, the difference was in activity, in the anti-epileptic target, SCN1A, the polymorphisms lead to different levels of protein in the brain.