Abstract
Clinical trials designed to compare antiretroviral regimens, investigate therapeutic drug monitoring, or measure pharmacometrics often include protease inhibitors (PIs), nonnucleoside reverse transcriptase inhibitors (NNRTIs), and nucleoside reverse transcriptase inhibitors, requiring the measurement of these antiretrovirals in plasma. Within the adult and pediatric AIDS Clinical Trials Group (ACTG), a network of Pharmacology Support Laboratories (PSLs) is a component of the group laboratory infrastructure and conducts these types of pharmacologic assays. The adult ACTG has developed a comprehensive quality assurance program for the conduct of clinical pharmacology protocols, one component of which is the antiretroviral proficiency testing (PT) program that has been implemented between the adult and pediatric pharmacology laboratories of the ACTG. PT testing samples were prepared and distributed in July 2001, February 2002, and July 2002. High, medium, and low concentrations of PIs (indinavir, saquinavir, amprenavir, lopinavir, ritonavir, and nelfinavir) and NNRTIs (nevirapine and efavirenz) were added to drug-free EDTA plasma and distributed, on dry ice, to eight ACTG PSLs. One testing laboratory used liquid chromatography-tandem mass spectrometry, and seven used high-performance liquid chromatography-UV analysis. A result was considered acceptable if it was within 20% deviation of the assigned concentration. For all concentrations of PIs evaluated, 96% of samples tested (430 of 448 measurements) met the acceptance criteria. For both NNRTIs, 100% of samples tested (140 of 140 measurements) met the acceptance criteria. In conclusion, the PT program results presented demonstrate excellent interlaboratory agreement for all antiretrovirals tested and provide support for the merger of plasma concentration data among laboratories for large clinical trials.