Isotope LabelingIsotopesNitrogen IsotopesAcenocoumarolOxygen IsotopesInternational Normalized RatioCarbon IsotopesAntiretroviral Therapy, Highly ActiveHIV InfectionsDouble-Blind MethodAnti-HIV AgentsZinc IsotopesTreatment OutcomeSulfur IsotopesTime FactorsDeuteriumIron IsotopesStrontium IsotopesRadioisotope Dilution TechniqueMass Spectrometry