Severe anemia secondary to a probable drug interaction between zidovudine and valproic acid.

A 42-year-old man with human immunodeficiency virus (HIV) infection and a history of complex partial seizures developed severe anemia after the addition of valproic acid to his stable antiretroviral regimen of zidovudine, lamivudine, and abacavir. The inhibition of zidovudine glucuronidation by valproic acid and the resultant zidovudine hematologic toxicity is the proposed mechanism of the interaction.