essentialmedgen.com
Home            Pharmacogenetic testing prior to prescribing anti-epileptics

Pharmacogenetics is a rapidly growing and important field. One of the aims of pharmacogenetics research is to be able to predict which patients are likely to have unpleasant side effects following the administration of a particular medication. A very recent development relates to the association of a specific genotype (the HLA B*1502 allele) with the drug-induced hypersensitivity that occurs in 5-10% of Han Chinese individuals who take carbamazepine. The hypersensitivity can be as severe as Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS-TEN), a prominent fever and rapid-onset blistering rash, which can be fatal.

A prospective pharmacogenetic study carried out in Taiwan by Chen et al. (2011) with 4000 patients, specifically advised those individuals who possessed the HLA B*1502 allele to take an alternative medication instead of carbamazepine. In this study, no cases of Stevens-Johnson syndrome subsequently occurred in this group of patients instead of the 10 cases of this severe side effect that would have been expected without this pharmacogenetic intervention. This particular allele is, however, not associated with hypersensitivity to this drug in European populations.

This study demonstrates the increasing importance of pharmacogenetics and specifically suggests that genotyping for this allele should be performed in Han Chinese patients before carbamazepine is prescribed.

Chen et al. (2011) New England Journal of Medicine 364:1126-1133.