Cell experiment:

In vitro growth inhibition (cytotoxicity) studies are conducted with S/GSK1349572 (0.16, 0.8, 4, and 20 nM) in proliferating human leukemic and lymphomic cell lines (IM-9, U-937, MT-4, and Molt-4) as well as in stimulated and unstimulated human PBMCs. ATP levels are quantified by using the CellTiter-Glo luciferase reagent to measure the ability of a compound to inhibit cell growth as an indicator of the compound's potential for cytotoxicity[1].

Animal experiment:

For rat and monkey PK studies, Dolutegravir is administered as the free acid or the sodium salt. All doses are presented in terms of the free acid. Dolutegravir is administered by intravenous (IV) short-term (within 2 min) bolus (1 mg/kg) to three male rats and two male monkeys. For single oral administration, Dolutegravir as a solution (5 mg/kg) is administered to three fasted male rats and two fasted male monkeys. Dolutegravir is administered as single oral doses of 5, 50, 100, and 250 mg/kg to non-fasted male rats (n=2/dose level) and 3, 10, and 50 mg/kg to non-fasted female monkeys. For intravenous administration, blood samples are collected from rats (0.2 mL via jugular vein cannula) and monkeys (approximately 0.2 or 0.5 mL via saphenous vein in a hindlimb) into Na2EDTA-treated syringes at 0.083, 0.25, 0.5, 1, 2, 4, 6, 8, and 24 h. For oral administration, samples are collected at 0.25 (rats only), 0.5, 1, 2, 4, 6 [rats (solution and suspension) and monkey (solution only)], 8, and 24 h. Following collection, the blood is immediately put on wet ice and then centrifuged within an hour at 1740 g for 10 min at 4℃ to obtain plasma. All samples are stored at approximately -20℃ or colder prior to analysis by using a method based on protein precipitation and LC-MS/MS analysis.

Integrase inhibitors are a new class of antiretroviral drugs blocking the action of HIV integrase, which catalyses several key steps in the life cycle of the virus and is essential for insertion of the viral genome into the host cell DNA. GSK1349572 is a next-generation HIV integrase (IN) inhibitor.

In vitro: GSK1349572 is a two-metal-binding HIV integrase strand transfer inhibitor whose mechanism of action was established through resistance passage experiments, integrase enzyme assays, mechanistic cellular assays and activity against viral strains resistant to other classes of anti-HIV agents. In a variety of cellular antiviral assays, GSK1349572 inhibited HIV replication with subnanomolar or low-nanomolar potency and with a selectivity index of 9,400. The protein-adjusted half-maximal effective concentration extrapolated to 100% human serum was 38 nM [1].

In vivo: No animial in vivo data are available for GSK1349572 so far.

Clinical trial: GSK1349572 was effective when given once daily without a pharmacokinetic booster and was well tolerated at all assessed doses. These findings support the assessment of once daily 50 mg GSK1349572 in phase 3 trials.

Reference:
[1] Kobayashi M, Yoshinaga T, Seki T, Wakasa-Morimoto C, Brown KW, Ferris R, Foster SA, Hazen RJ, Miki S, Suyama-Kagitani A, Kawauchi-Miki S, Taishi T, Kawasuji T, Johns BA, Underwood MR, Garvey EP, Sato A, Fujiwara T.  In Vitro antiretroviral properties of S/GSK1349572, a next-generation HIV integrase inhibitor. Antimicrob Agents Chemother. 2011 Feb;55(2):813-21.
[2] van Lunzen J, Maggiolo F, Arribas JR, Rakhmanova A, Yeni P, Young B, Rockstroh JK, Almond S, Song I, Brothers C, Min S.  Once daily dolutegravir (S/GSK1349572) in combination therapy in antiretroviral-naive adults with HIV: planned interim 48 week results from SPRING-1, a dose-ranging, randomised, phase 2b trial. Lancet Infect Dis. 2012 Feb;12(2):111-8.