JAC Advance Access originally published online on February 18, 2005
Journal of Antimicrobial Chemotherapy 2005 55(4):542-545; doi:10.1093/jac/dki043
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Boosted saquinavir hard gel formulation exposure in HIV-infected subjects: ritonavir 100 mg once daily versus twice daily
1 PK Research Ltd, St Stephen's Centre, Chelsea and Westminster Hospital, 369 Fulham Road, London SW10 9NH, UK; 2 University of Liverpool, Liverpool, UK; 3 Roche, Welwyn, UK
* Corresponding author. Tel: +44-20-8846-6507; Fax: +44-20-8746-5628; Email: marta.boffito{at}chelwest.nhs.uk
Objectives: The amount of ritonavir needed to enhance saquinavir hard gel (hg) plasma concentrations is unclear. Reduced ritonavir dosing may help to reduce ritonavir-related side effects and costs. This study examined the pharmacokinetics of twice-daily saquinavir-hg (1000 mg) in the presence of ritonavir 100 mg, dosed twice-daily and once-daily on one single occasion.
Methods: Eighteen HIV-infected adults taking saquinavir/ritonavir 1000/100 mg twice-daily underwent pharmacokinetic (PK) assessment of saquinavir/ritonavir on day 1 following a morning saquinavir/ritonavir dose. On day 2, PK assessment was repeated when subjects took saquinavir without ritonavir. Drug intake (with a standard meal containing 20 g of fat) was timed on days –1, 1 and 2. Geometric mean ratios (GMR) and 95% confidence intervals (CI) were calculated to assess changes in saquinavir PK parameters.
Results: Geometric mean saquinavir AUC0–12, Ctrough, Cmax and elimination half-life on days 1 and 2 were 14 389 and 9590 ng·h/mL, 331 and 234 ng/mL, 2503 and 1893 ng/mL and 2.80 and 2.82 h, respectively. The GMR (95% CI) for these parameters were 0.67 (0.53–0.84), 0.71 (0.48–1.04), 0.76 (0.58–0.98) and 1.01 (0.86–1.18), respectively.
Conclusions: Withholding a ritonavir dose significantly reduces overall saquinavir exposure and Cmax, but had no impact on the elimination half-life. These data establish the need to administer saquinavir and ritonavir simultaneously.
Keywords: saquinavir , ritonavir , pharmacokinetics , boosted protease inhibitors
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