Clinically Significant Drug Interaction between Tipranavir-Ritonavir and Phenobarbital in an HIV-Infected Subject

Abstract

To The Editor—HIV protease inhibitor tipranavir (TPV) with boosting of ritonavir (RTV) is used for anti-HIV treatment in multiexperienced patients [1]. TPV is known as a substrate and inducer of cytochrome P450 isoenzyme 3A4 (CYP3A4) [1]. Phenobarbital, widely used as an anticonvulsant, undergoes metabolism by CYP2C9 and CYP2C19 and is a CYP3A4 inducer [2]. No data are yet available on coadministration of TPV-RTV and phenobarbital and related risk of drug interaction. We report a case here.