Comparison of theIn VivoPharmacokinetics andIn VitroDissolution of Raltegravir in HIV Patients Receiving the Drug by Swallowing or by Chewing

Abstract

ABSTRACTThe pharmacokinetics of raltegravir (RAL) in HIV patients is characterized by high interpatient/intrapatient variability. We investigated the potential contribution of the drug pharmaceutical formulation to RAL pharmacokinetics. We first comparedin vivothe pharmacokinetics of RAL for 67 patients to whom the drug was administered by swallowing the intact tablet with those obtained from 13 HIV-infected patients who chewed the RAL tablet due to swallowing difficulties. Subsequently, we evaluatedin vitrothe dissolution of RAL tablets under different conditions. In thein vivostudy, we found that patients given RAL by chewing the tablets presented pharmacokinetic profiles characterized by significantly higher RAL absorption than did patients receiving the drug by swallowing. Thein vitrostudies showed that when the whole tablets were exposed to an acidic medium, the release of RAL was very low, whereas when the tablets were crushed, the profiles presented significantly higher concentrations of RAL. Crushed tablets tested in water or in a pH 6.8 buffer exhibited prompt and complete dissolution of RAL. HIV-infected patients receiving RAL by chewing the tablet showed higher drug absorption and reduced pharmacokinetic variability compared with patients swallowing the intact tablet. This is related to problems in tablet disintegration and to erratic drug absorption. The amelioration of the RAL pharmaceutical formulation could improve drug pharmacokinetics.