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Effect of Adherence as Measured by MEMS, Ritonavir Boosting, and CYP3A5 Genotype on Atazanavir Pharmacokinetics in Treatment‐Naive HIV‐Infected Patients
Author(s) -
Savic R M,
BarrailTran A,
Duval X,
Nembot G,
Panhard X,
Descamps D,
Verstuyft C,
Vrijens B,
Taburet AM,
Goujard C,
Mentré F
Publication year - 2012
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1038/clpt.2012.137
Subject(s) - atazanavir , ritonavir , pharmacokinetics , pharmacology , medicine , dosing , bioequivalence , therapeutic drug monitoring , pharmacogenetics , virology , human immunodeficiency virus (hiv) , genotype , viral load , chemistry , antiretroviral therapy , biochemistry , gene
We investigated population pharmacokinetics and pharmacogenetics of ritonavir‐boosted atazanavir (ATV), using drug intake times exactly recorded by the Medication Event Monitoring System. The ANRS 134–COPHAR 3 trial was conducted in 35 HIV‐infected treatment‐naive patients. ATV (300 mg), ritonavir (100 mg), and tenofovir (300 mg) + emtricitabine (200 mg), in bottles with MEMS caps, were taken once daily for 6 months. Six blood samples were collected at week 4 to measure drug concentrations, and trough levels were measured bimonthly. A model integrating ATV and ritonavir pharmacokinetics and pharmacogenetics used nonlinear mixed effects. Use of exact dosing data halved unexplained variability in ATV clearance. The ritonavir–ATV interaction model suggested that optimal boosting effect is achievable at lower ritonavir exposures. Patients with at least one copy of the CYP3A5*1 allele exhibited 28% higher oral clearance. We provide evidence that variability in ATV pharmacokinetics is defined by adherence, CYP3A5 genotype, and ritonavir exposure. Clinical Pharmacology & Therapeutics (2012); 92 5, 575–583. doi: 10.1038/clpt.2012.137