Low N-acetylating capacity in patients with Stevens-Johnson syndrome and toxic epidermal necrolysis.

Low constitutive N-acetylating capacity has been implicated as a predisposing factor for the development of adverse reactions to certain drugs. This prompted us to investigate whether the N-acetylating capacity of patients with serious cutaneous adverse reactions, i.e., Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) differed from that of healthy control subjects. N-acetylating activity was measured in hair root cells by preparing a homogenate from freshly extracted hair roots and assessing acetyl-CoA-dependent N-acetylation by RP-HPLC using 2-aminofluorene as a substrate. Samples were obtained from hospitalized patients suffering from acute SJS and TEN or from healthy controls. All patients with SJS and TEN were found to have a low N-acetylating capacity (0.85 nmol/mg/min compared to 2.21 nmol/mg/min in controls, p < 0.05). Based on these findings, a low constitutive N-acetylating capacity may be one of the predisposing factors for the development of serious cutaneous adverse reactions to drugs that require N-acetylation in these patients.