title: Development of a population simulation model for HIV monotherapy virological outcomes using lamivudine.
abstract: Current highly active antiretroviral therapy (HAART) requires the use of combinations of three drugs to minimize the early emergence of drug-resistant HIV strains. Therefore, long-term monotherapy data with new agents are unavailable. However, the development of computer models for Monte-Carlo-type simulations of antiviral monotherapy, which incorporate HIV infection dynamic distributions from previously studied populations, together with pharmacokinetics and pharmacodynamic parameters of the new agent, could serve as an important tool. The nucleoside lamivudine (3TC) was used as a representative drug to standardize an improved pharmacodynamic and infection dynamic monotherapy model. 3TC plasma concentration versus time profiles was used to drive the cellular accumulation of 3TC-triphosphate (TP) in primary human lymphocytes in the model, over a 16 week period. The fraction of HIV reverse transcription inhibited was calculated using the median inhibitory concentration and intracellular 3TC-TP levels. Virus loads and activated CD4+ T-cell counts were generated for 2,200 theoretical individuals and compared with the outcomes of an actual 3TC monotherapy trial at the same dose. Pharmacokinetic variance alone did not account for the interindividual HIV-load variability. However, selection of appropriate distributions of the various pharmacokinetic and infection dynamics parameters produced a similar range of virus load reductions to actual observations. Therefore, once parameter and variance distributions are standardized, this modelling approach could be helpful in planning clinical trials and predicting the antiviral contribution of each agent in a HAART modality.
authors.affiliation: Center for AIDS Research and Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA. shurwit@emory.edu
authors.forename: Selwyn J
authors.initials: SJ
authors.lastname: Hurwitz
authors.forename: Ghazia
authors.initials: G
authors.lastname: Asif
authors.forename: Raymond F
authors.initials: RF
authors.lastname: Schinazi
mesh_terms: D019380:Anti-HIV Agents / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use*; D018791:CD4 Lymphocyte Count; D002986:Clinical Trials as Topic; D003570:Cytidine Triphosphate / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D054306:Dideoxynucleotides / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology* / Q000627:therapeutic use*; D006678:HIV / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000502:physiology; D015658:HIV Infections / Q000188:drug therapy* / Q000276:immunology / Q000821:virology*; D006801:Humans; D020128:Inhibitory Concentration 50; D007700:Kinetics; D019259:Lamivudine / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D008954:Models, Biological; D009010:Monte Carlo Method; D018894:Reverse Transcriptase Inhibitors / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D016896:Treatment Outcome; D019562:Viral Load
chemical_list: D019380:Anti-HIV Agents; D054306:Dideoxynucleotides; D018894:Reverse Transcriptase Inhibitors; C417268:lamivudine triphosphate; D019259:Lamivudine; D003570:Cytidine Triphosphate