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Pharmacokinetics of efavirenz (EFV) alone and in combination therapy with nelfinavir (NFV) in HIV‐1 infected patients
Author(s) -
Paola Villani,
Mario Regazzi,
Francesco Castelli,
Pierluigi Viale,
Carlo Torti,
Elena Seminari,
Renato Maserati
Publication year - 1999
Publication title -
british journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.216
H-Index - 146
eISSN - 1365-2125
pISSN - 0306-5251
DOI - 10.1046/j.1365-2125.1999.00071.x
Subject(s) - nelfinavir , pharmacokinetics , efavirenz , pharmacology , medicine , chemistry , human immunodeficiency virus (hiv) , viral load , antiretroviral therapy , virology
Aims To define the pharmacokinetic profile of efavirenz (EFV) in HIV‐1 infected patients, when administered alone or with nelfinavir (NFV).Methods Eleven HIV‐positive patients, in steady‐state treatment with EFV and 11 patients in steady‐state treatment with EFV+NFV, were evaluated. Blood samples for pharmacokinetic analysis were obtained during a dosage interval. Plasma concentrations of EFV were determined by h.p.l.c.Results No significant difference was found between the principal pharmacokinetic parameters of EFV when administered alone or in combination with NFV (mean AUC: 57.1–7727.3 vs 60.9±12.3 μg ml −1 h; mean CL/F: 0.18±0.072 vs 0.16±0.04 l h −1 kg −1 ; mean C max : 4.0±1.7 vs 4.3±1.2 μg ml −1 , and mean t max : 4.1±1.7 vs 3.5±0.5 h) Mean trough plasma concentrations (C0) of EFV were 1.64±0.93 μg ml −1 , with and without NFV. A good correlation was found between C0 and AUC(0,24h) (r=0.96; P <0.01).Conclusions Despite the common metabolic pathway, there was no significant influence of NFV on the pharmacokinetics of EFV. EFV exhibits a relatively low interindividual variability and a dosing regimen of 600 mg day −1 assures plasma concentrations that are adequate for inhibition of viral replication.