Generic products reduce the costs of HIV treatment. Few generic second-line antiretroviral products are available. We assessed pharmacokinetics, safety and efficacy of generic lopinavir/ritonavir (LPV/r) produced by the Government Pharmaceutical Organization (GPO) of Thailand in Thai HIV-infected adults. Methods: This was a single-arm prospective study. Patients with plasma HIV-1 RNA<50 copies/ml for ≥24 weeks, who were protease inhibitor (PI)-naive or experienced, were eligible. Patients

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... d generic LPV/r tablets, 400/100 mg twice daily. At week 4, therapeutic drug monitoring was performed and analysed by validated HPLC. In patients using Kaletra® (Abbott Laboratories, North Chicago, IL, USA) soft gel capsules (SGC) or generic LPV/r tablets produced by Mylan (Canonsburg, PA, USA; formerly Matrix, Hyderabad, India) prior to study entry, we compared the plasma minimum concentrations (C min ) of the different formulations. Plasma HIV-1 RNA and safety were assessed until week 48. Results: A total of 70 patients (32 males) were enrolled. Mean (sd) age was 40.7 (7.9) years and mean (sd) body weight was 60.3 (9.0) kg. Before study entry, all patients were virologically suppressed using a PI-based regimen; 62 (88.6%) were using LPV/r (Kaletra® SGC n=22 and Mylan generic tablets n=40). Mean (sd) C min of GPO lopinavir and GPO ritonavir at week 4 were 7.1 (2.9) mg/l and 0.39 (0.21) mg/l, respectively, and not significantly different from the C min when taking Kaletra® SGC or Mylan generic tablets. After 48 weeks, 95.6% of patients maintained plasma HIV-1 RNA<50 copies/ml. Four grade 3 and no grade 4 adverse events were reported. Conclusions: Generic LPV/r showed adequate levels, good tolerability and excellent 48-week efficacy. Lopinavir (LPV) is a protease inhibitor (PI) that is coformulated with ritonavir (RTV). RTV enhances the pharmacokinetics of LPV by inhibiting its CYP450-3Amediated metabolism [1] . The combination is a preferred option, as part of second-line HAART in developing countries [2] . Boosted LPV (LPV/r) is a potent antiretroviral, in experienced and in PI-naive patients [3, 4] . The original solid oral formulation of LPV/r was a soft gel capsule (SGC) in a 133/33-mg formulation, which requires refrigerated storage and needs to be taken with food. A heat-stable tablet formulation of this fixed combination (Kaletra ® /Aluvia ® 200/50 mg) is now available. This formulation is bioequivalent to the SGC, does not need refrigerated storage and has little to no food effect [5] , which are major advantages, especially for resource-limited settings. However, heatstable tablets of LPV/r are currently not available in Thailand due to a compulsory licensing issue between