title: Population pharmacokinetics and pharmacodynamics of efavirenz, nelfinavir, and indinavir: Adult AIDS Clinical Trial Group Study 398.
abstract: The present population pharmacokinetic (PK) and pharmacodynamic (PD) study modeled the effects of covariates including drug adherence and the coadministration of protease inhibitors (PIs) on the pharmacokinetics of efavirenz (EFV) and the relationship between EFV exposure and virological failure in patients who failed initial PI treatment in Adult AIDS Clinical Trial Group (AACTG) study 398. We also report on the population PKs of the PIs nelfinavir (NFV) and indinavir (IDV). AACTG study 398 patients received EFV, amprenavir, adefovir dipivoxil, and abacavir and were randomized to take, in addition, one of the following: NFV, IDV, saquinavir (SQV), or placebo. The PK databases consisted of 531 EFV concentrations (139 patients), 219 NFV concentrations (75 patients), and 66 IDV concentrations (11 patients). Time to virological failure was ascertained for all patients in the PK databases. PK data were fit with a population PK model that assumed exclusive hepatic elimination (the well-stirred model). Notable findings with respect to EFV PK and PD are as follows. (i) The hepatic clearance of EFV is unaltered by NFV, IDV, or SQV coadministration. (ii) The hepatic clearance of EFV appears to be 28% higher in white non-Hispanics than in African Americans and Hispanics (P = 0.03). (iii) Higher adherence scores (as measured with the Medication Event Monitoring System) are associated with marginally increased levels of exposure to EFV. (iv) In patients with no prior experience with nonnucleoside reverse transcriptase inhibitors (NNRTIs), a given percent increase in the oral clearance (CL/F) of EFV is associated with a greater percent increase in the hazard of virological failure (P < 0.0003). Among NNRTI-experienced patients, however, hazard is relatively uncorrelated with EFV CL/F.
authors.affiliation: Department of Laboratory Medicine and Biopharmaceutical Sciences, University of California, San Francisco, San Francisco, California 94143, USA.
authors.forename: Marc
authors.initials: M
authors.lastname: Pfister
authors.forename: Line
authors.initials: L
authors.lastname: Labbé
authors.forename: Scott M
authors.initials: SM
authors.lastname: Hammer
authors.forename: John
authors.initials: J
authors.lastname: Mellors
authors.forename: Kara K
authors.initials: KK
authors.lastname: Bennett
authors.forename: Susan
authors.initials: S
authors.lastname: Rosenkranz
authors.forename: Lewis B
authors.initials: LB
authors.lastname: Sheiner
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000188:drug therapy* / Q000378:metabolism; D000328:Adult; D000480:Alkynes; D001499:Bayes Theorem; D048588:Benzoxazines; D003521:Cyclopropanes; D004347:Drug Interactions; D005260:Female; D017320:HIV Protease Inhibitors / Q000097:blood / Q000493:pharmacokinetics* / Q000627:therapeutic use; D006801:Humans; D019469:Indinavir / Q000097:blood / Q000627:therapeutic use*; D008297:Male; D008954:Models, Biological; D019888:Nelfinavir / Q000097:blood / Q000627:therapeutic use*; D010078:Oxazines / Q000097:blood / Q000493:pharmacokinetics* / Q000627:therapeutic use; D011159:Population Surveillance; D017211:Treatment Failure
chemical_list: D000480:Alkynes; D048588:Benzoxazines; D003521:Cyclopropanes; D017320:HIV Protease Inhibitors; D010078:Oxazines; D019469:Indinavir; D019888:Nelfinavir; C098320:efavirenz