Medline ® Abstract for Reference 36

BACKGROUND: Aromatic anticonvulsant-induced severe cutaneous adverse drug reactions (SCARs), including Stevens-Johnson syndrome (SJS), toxic epidermal necrosis (TEN), and drug rash with eosinophilia and systemic symptoms (DRESS), are fatal immune-mediated adverse drug reactions. CYP2C19, a cytochrome P450 isoform, plays a role in metabolic rate of aromatic anticonvulsant. HLA-B*1502 has also been demonstrated to be associated with carbamazepine-induced SJS-TEN.

METHODS: Forty case patients who were diagnosed with SCARs after initiation of phenobarbital (PB), phenytoin (PHT), or carbamazepine (CBZ) for 1-8 wk and forty control patients who received PB, PHT, or CBZ at least 2 months with no adverse drug reactions were enrolled in the study. The genotypes of CYP2C19*1, CYP2C19*2, and HLA-B*1502 were analyzed using allele-specific polymerase chain reaction technique. Clinical characteristics of SCARs patients who used different drugs were also analyzed.

RESULTS: There was no significant difference in sex, onset of symptoms, laboratory results, treatment, and length of stay among patients with SCARs due to PB, PHT, orCBZ. The patients with CYP2C19*2 variant had a trend to have a likelihood to develop SCARs more than the patients with CYP2C19 wild type (OR = 2.5, 95% CI (0.96-67.3) p = 0.06). In subgroup analysis, the patients with CYP2C19*2 variant were at four times increased risk of SCARs from phenobarbital more than the patients with CYP2C19 wild type (OR = 4.5, 95% CI (1.17-17.37) p < 0.03). There was no association between the HLA-B*1502 and aromatic anticonvulsant-induced severe cutaneous adverse reactions (SCARs).

CONCLUSION: CYP2C19*2 variant may play a role in the genetic predisposition of SCARs from phenobarbital.