Clinical pharmacokinetics of nelfinavir and its metabolite M8 in human immunodeficiency virus (HIV)-positive and HIV-hepatitis C virus-coinfected subjects

In order to evaluate the potential risk of nelfinavir (NFV) accumulation in human immunodeficiency virus (HIV)-hepatitis C virus (HCV)-coinfected patients with liver disease, we investigated the concentrations of NFV and M8, the active metabolite of NFV, in plasma HIV-positive (HIV+) patients coinfected with HCV. A total of 119 HIV+ subjects were included in our study: 67 HIV+ patients, 32 HIV+ and HCV-positive (HCV+) patients without cirrhosis, and 20 HIV+ and HCV+ patients with cirrhosis. Most of the enrolled patients (chronically treated) were taking NFV at the standard dosage of 1,250 mg twice a day. To assay plasma NFV and M8 concentrations, patients underwent serial plasma samplings during the dosing interval at steady state. Plasma NFV and M8 concentrations were measured simultaneously by a high-performance liquid chromatography method with UV detection. The HIV+ and HCV+ patients with and without cirrhosis had significantly lower NFV oral clearances than the HIV+ and HCV-negative individuals (28 and 58% lower, respectively; P <0.05), which translated into higher areas under the concentration-time curves for cirrhotic and noncirrhotic patients. The NFV absorption rate was significantly lower in cirrhotic patients, resulting in a longer time to the maximum concentration in serum. The mean ratios of the M8 concentration/NFV concentration were significantly lower (P <0.05) in HIV+ and HCV+ subjects with cirrhosis (0.06 ± 0.074) than in the subjects in the other two groups. The mean ratios for M8 and NFV were not statistically different between HIV+ and HCV-negative patients (0.16 ± 0.13) and HIV+ and HCV+ patients without cirrhosis (0.24 ± 0.17), but the interpatient variability was high. Our results indicate that the pharmacokinetics of NFV and M8 are altered in HIV+ and HCV+ patients, especially those with liver cirrhosis. Therefore, there may be a role for therapeutic drug monitoring in individualizing the NFV dosage in HIV-HCV-coinfected patients.