Pharmacokinetic modeling of plasma and intracellular concentrations of raltegravir in healthy volunteers

Lingzhi Wang, Gaik Hong Soon, Kok Yong Seng, Jun Li, Edmund Lee, Eu Leong Yong, Boon Cher Goh, Charles Flexner, Lawrence Lee

Research output: Contribution to journalArticle

Abstract

Raltegravir is a potent inhibitor of HIV integrase. Persistently high intracellular concentrations of raltegravir may explain sustained efficacy despite high pharmacokinetic variability. We performed a pharmacokinetic study of healthy volunteers. Paired blood samples for plasma and peripheral blood mononuclear cells (PBMCs) were collected predose and 4, 8, 12, 24, and 48 h after a single 400-mg dose of raltegravir. Samples of plasma only were collected more frequently. Raltegravir concentrations were determined using liquid chromatography-mass spectrometry. The lower limits of quantitation for plasma and PBMC lysate raltegravir were 2 nmol/liter and 0.225 nmol/liter, respectively. Noncompartmental analyses were performed using WinNonLin. Population pharmacokinetic analysis was performed using NONMEM. Six male subjects were included in the study; their median weight was 67.4 kg, and their median age was 33.5 years. The geometric mean (GM) (95% confidence interval shown in parentheses) maximum concentration of drug (Cmax), area under the concentration-time curve from 0 to 12 h (AUC0-12), and area under the concentration-time curve from 0 h to infinity (AUC0-∞) for raltegravir in plasma were 2,246 (1,175 to 4,294) nM, 10,776 (5,770 to 20,126) nM · h, and 13,119 (7,235 to 23,788) nM · h, respectively. The apparent plasma raltegravir half-life was 7.8 (5.5 to 11.3) h. GM intracellular raltegravir Cmax, AUC0-12, and AUC0-∞ were 383 (114 to 1,281) nM, 2,073 (683 to 6,290) nM · h, and 2,435 (808 to 7,337) nM · h (95% confidence interval shown in parentheses). The apparent intracellular raltegravir half-life was 4.5 (3.3 to 6.0) h. Intracellular/plasma ratios were stable for each patient without significant time-related trends over 48 h. Population pharmacokinetic modeling yielded an intracellular-to-plasma partitioning ratio of 11.2% with a relative standard error of 35%. The results suggest that there is no intracellular accumulation or persistence of raltegravir in PBMCs.

Original languageEnglish (US)
Pages (from-to)4090-4095
Number of pages6
JournalAntimicrobial agents and chemotherapy
Volume55
Issue number9
DOIs
StatePublished - Sep 1 2011

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)
  • Infectious Diseases

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