Coadministration with valproic acid alone has not been studied. Valproic acid circulates in plasma as the valproate ion. Valproate is mainly glucuronidated by UGTs 1A6, 1A9 and 2B7 and metabolized by CYP2C9 and CYP2C19. There is no evidence that atazanavir inhibits or induces these UGTs and CYPs, however concentrations of valproate may decrease due to induction of UGTs and CYP2C9/19 by ritonavir. Careful monitoring of valproate concentrations and/or therapeutic effect is recommended. When atazanavir/ritonavir was administered with minocycline or minocycline plus valproic acid, there was no evidence of an effect of valproate on atazanavir exposure.