Plasma and intracellular population pharmacokinetic analysis of tenofovir in HIV-1-infected patients.

TitlePlasma and intracellular population pharmacokinetic analysis of tenofovir in HIV-1-infected patients.
Publication TypePublication
Year of Publication2011
AuthorsBaheti G, Kiser JJ, Havens PL, Fletcher CV
JournalAntimicrob Agents Chemother
Date Published2011 Nov
KeywordsAdenine, Adolescent, Adult, Chromatography, Liquid, Female, Humans, Male, Middle Aged, Organophosphonates, Tandem Mass Spectrometry, Tenofovir, Young Adult

<p>The relationships among the dose of tenofovir disoproxil fumarate (TDF), tenofovir (TFV) plasma concentrations, and intracellular TFV diphosphate (TFV-DP) concentrations are poorly understood. Our objective was to characterize TFV and TFV-DP relationships. Data were pooled from two studies in HIV-infected persons (n = 55) on stable antiretroviral therapy. TFV and TFV-DP were measured with validated liquid chromatography/tandem mass spectrometry (LC/MS/MS) methods. Nonlinear mixed effects modeling (NONMEM 7) was used to develop the population model and explore the influence of covariates on TFV. A sequential analysis approach was utilized. A two-compartment model with first-order absorption best described TFV PK (FOCEI). An indirect stimulation of response model best described TFV-DP, where formation of TFV-DP was driven by plasma TFV concentration. Final plasma population estimates were as follows: absorption rate constant, 1.03 h(-1); apparent clearance (CL/F), 42 liters/h (33.5% interindividual variability [IIV]); intercompartment clearance, 181 liters/h; apparent central distribution volume (Vc/F), 273 liters (64.8% IIV); and apparent peripheral distribution volume (Vp/F), 440 liters (46.5% IIV). Creatinine clearance was the most significant covariate on CL/F and Vc/F. The correlation between CL/F and Vc/F was 0.553. The indirect response model for TFV-DP resulted in estimates of the maximal intracellular concentration (E(max)), the TFV concentration producing 50% of E(max) (EC(50)), and the intracellular elimination rate constant (k(out)) of 300 fmol/10(6) cells (82% IIV), 100 ng/ml (106% IIV), and 0.008 h(-1), respectively. The estimated k(out) gave an 87-h TFV-DP half-life. A predictive check assessment indicated satisfactory model performance. This model links formation of TFV-DP with plasma TFV concentrations and should facilitate more informed investigations of TFV clinical pharmacology.</p>

Alternate JournalAntimicrob Agents Chemother
PubMed ID21896913
PubMed Central IDPMC3194996
Grant ListP01 AI074340 / AI / NIAID NIH HHS / United States
U01 HD040474 / HD / NICHD NIH HHS / United States
U01 HD040533 / HD / NICHD NIH HHS / United States
U01 HD 040474 / HD / NICHD NIH HHS / United States