Effect of Gender and HIV Infection on Zidovudine and Lamivudine Pharmacokinetics

Inclusion Criteria: * Documented physician-diagnosed HIV-infection (HIV+ antibody or plasma HIV-RNA+); HIV-negative volunteers must have a negative HIV-ELISA. * Age 18 to 55 years; * Either antiretroviral naïve, or no HIV-therapy in the preceding 6 months; * Planned antiretroviral regimen includes standard doses of ZDV plus 3TC as part of the antiretroviral regimen. Once- or twice-daily 3TC will be allowed. Exclusion Criteria: * Any medical condition that in the opinion of the investigators would jeopardize the intent of the study. * In the opinion of the investigator, any concomitant immunomodulatory medications, chemotherapeutic agents, investigational drugs, and alternative therapies, including, glucocorticoids, recombinant growth factors or cytokines (e.g. Granulocyte-macrophage colony-stimulating factor, Granulocyte colony-stimulating factor, interferon-alpha or gamma, human growth hormone, etc), ribavirin, birth-control pills, and sex hormones that could interfere with the cellular pharmacology of the study medications; * Concomitant medications that interfere with renal drug clearances including, tenofovir, adefovir, cidofovir, ganciclovir, probenecid, or any similarly problematic medication in the opinion of the investigators; * Concomitant warfarin or daily aspirin (to prevent excess bleeding from biopsy). * Pregnancy or a plan to become pregnant, or menopause; * Any \> or = grade II abnormality in hemoglobin, absolute neutrophil count, routine liver function tests, serum creatinine, or other organ function abnormalities. * Any medical or personal condition that, in the judgment of the investigators, may influence the subject's ability to comply with study conditions, such as active mental illnesses, or plans to leave the geographical area. * Inability to give informed consent. * Triple nucleoside analog reverse transcriptase regimens.