title: The steady-state pharmacokinetics of atazanavir/ritonavir in HIV-1-infected adult outpatients is not affected by gender-related co-factors.
abstract: OBJECTIVE
  Pharmacokinetic differences, contributing to drug-related side effects, between men and women have been reported for HIV protease inhibitors. As only limited and inconclusive data on ritonavir-boosted atazanavir are available, we evaluated the respective steady-state pharmacokinetics in 48 male and 26 female HIV-1-infected adults receiving atazanavir/ritonavir 300/100 mg once-daily as part of their antiretroviral therapy.
  
  
  METHODS
  Pharmacokinetic profiles (24 h) of atazanavir/ritonavir were assessed and measured by HPLC/tandem mass spectrometry. Geometric mean (GM; ANOVA) of minimum and maximum plasma drug concentrations (C(min) and C(max)), area under the concentration-time curve (AUC) and total clearance (CL(total)) were compared between the sexes and correlated to demographic (age, gender and ethnicity), physiological (weight and body mass index) and clinical (CD4+ cell count, HIV-RNA, co-medication and hepatitis serology) co-factors.
  
  
  RESULTS
  The GM of the atazanavir AUC, C(max) and C(min) of men versus women were 32 643 versus 36 232 ng.h/mL [GM ratio (GMR) = 1.11, P = 0.435], 2802 versus 3211 ng/mL (GMR = 1.15, P = 0.305) and 398 versus 470 ng/mL (GMR = 1.18, P = 0.406), respectively. Although weight (80.6 versus 63.9 kg, P = 0.001) and body weight-adjusted atazanavir dose (3.84 versus 4.60 mg/kg, P = 0.013) were different between the sexes, no significant correlation to atazanavir pharmacokinetics was observed. A linear regression analysis detected significant correlations of atazanavir C(min) with ritonavir AUC (P < 0.001) and the co-administration of methadone oral solution (P = 0.032), and inverse correlations with the time since the first HIV infection diagnosis (P = 0.003) and the number of previous antiretroviral treatments (P = 0.022).
  
  
  CONCLUSIONS
  Atazanavir/ritonavir steady-state pharmacokinetics was comparable in men and women, despite gender-related significant differences in atazanavir dose/body weight. The administration of atazanavir/ritonavir is pharmacokinetically safe; 95% of all trough samples were above the recommended plasma concentration of 150 ng/mL.
authors.affiliation: Pharmazentrum Frankfurt, Institute of Clinical Pharmacology, Johann Wolfgang Goethe University, Frankfurt, Germany. hentig@em.uni-frankfurt.de
authors.forename: Nils
authors.initials: N
authors.lastname: von Hentig
authors.forename: Errol
authors.initials: E
authors.lastname: Babacan
authors.forename: Tessa
authors.initials: T
authors.lastname: Lennemann
authors.forename: Gabi
authors.initials: G
authors.lastname: Knecht
authors.forename: Amina
authors.initials: A
authors.lastname: Carlebach
authors.forename: Sebastian
authors.initials: S
authors.lastname: Harder
authors.forename: Schlomo
authors.initials: S
authors.lastname: Staszewski
authors.forename: Annette
authors.initials: A
authors.lastname: Haberl
mesh_terms: D000328:Adult; D019540:Area Under Curve; D000069446:Atazanavir Sulfate; D002851:Chromatography, High Pressure Liquid; D005260:Female; D015658:HIV Infections / Q000188:drug therapy*; D017320:HIV Protease Inhibitors / Q000008:administration & dosage / Q000493:pharmacokinetics*; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D009842:Oligopeptides / Q000008:administration & dosage / Q000493:pharmacokinetics*; D010045:Outpatients; D010949:Plasma / Q000737:chemistry; D011725:Pyridines / Q000008:administration & dosage / Q000493:pharmacokinetics*; D019438:Ritonavir / Q000008:administration & dosage / Q000493:pharmacokinetics*; D012723:Sex; D053719:Tandem Mass Spectrometry
chemical_list: D017320:HIV Protease Inhibitors; D009842:Oligopeptides; D011725:Pyridines; D000069446:Atazanavir Sulfate; D019438:Ritonavir