A Comparison of the Steady‐State Pharmacokinetics and Safety of Abacavir, Lamivudine, and Zidovudine Taken as a Triple Combination Tablet and as Abacavir plus a Lamivudine‐Zidovudine Double Combination Tablet by HIV‐1‐Infected Adults

Study Objective. To investigate the steady-state pharmacokinetics of a triple combination tablet containing abacavir (ABC) 300 mg, lamivudine (3TC) 150 mg, and zidovudine (ZDV) 300 mg taken twice/day, and those of ABC 300 mg twice/day plus a double combination tablet containing 3TC 150 mg and ZDV 300 mg twice/day (ABC-COM). Design. Open-label, crossover study. Setting. Two hospital-based clinical research units. Patients. Twelve men infected with human immunodeficiency virus-1. Intervention. Steady-state pharmacokinetics of ABC, 3TC, and ZDV were assessed after dosing with ABC-COM and the triple combination tablet. Measurements and Main Results. Steady-state pharmacokinetics of ABC, 3TC, and ZDV were similar for the triple combination tablet versus ABC-COM for the following: geometric mean (GM) area under the serum concentration-time curve, ABC 6.08 versus 5.87, 3TC 5.51 versus 5.53, and ZDV 1.38 versus 1.46 μg·hr/ml; GM maximum serum concentration (Cmax-ss), ABC 3.09 versus 3.19, 3TC 1.26 versus 1.40, and ZDV 1.19 versus 1.15 μg/ml; median time to Cmax-ss, ABC 0.75 versus 0.75, 3TC 1.50 versus 1.24, and ZDV 0.75 versus 0.75 hours; and GM oral clearance, ABC 51 versus 49, 3TC 27 versus 27, and ZDV 217 versus 206 L/hour. The GM half-lives of ABC and ZDV were similar for both treatments, 1.69 versus 1.58 and 2.30 versus 2.08 hours, respectively. Conclusion. Steady-state pharmacokinetics of ABC, 3TC, and ZDV were similar in patients who took them as ABC-COM or as a triple combination tablet.