Pharmacokinetic and Safety Analyses of Tenofovir and TenofovirEmtricitabine Vaginal Tablets in Pigtailed Macaques

Vaginal rapidly disintegrating tablets (RDTs) containing tenofovir (TFV) or TFV and emtricitabine (FTC) were evaluated for safety and pharmacokinetics in pigtailed macaques. Two separate animal groups (n = 4) received TFV (10 mg) or TFV- FTC (10 mg each) RDTs, administered near the cervix. A third group (n = 4) received 1 ml TFV gel. Blood plasma, vaginal tissue biopsy specimens, and vaginal fluids were collected before and after product application at 0, 0.5, 1, 4, and 24 h. A disintegration time of < 30 min following vaginal application of the RDTs was noted, with negligible effects on local inflammatory cytokines, vaginal pH, and microflora. TFV pharmacokinetics were generally similar for both RDTs and gel, with peak median concentrations in vaginal tissues and vaginal secretions being on the order of 104 to 105 ng/ g (147 to 571 = M) and 106 ng/ g (12 to 34 mM), respectively, at 1 to 4 h postdose. At 24 h, however, TFV vaginal tissue levels were more sustained after RDT dosing, with median TFV concentrations being approximately 1 log higher than those with gel dosing. FTC pharmacokinetics after combination RDT dosing were similar to those of TFV, with peak median vaginal tissue and fluid levels being on the order of 104 ng/ g (374 = M) and 106 ng/ g (32 mM), respectively, at 1 h postdose with levels in fluid remaining high at 24 h. RDTs are a promising alternative vaginal dosage form, delivering TFV and/ or FTC at levels that would be considered inhibitory to simian- human immunodeficiency virus in the macaque vaginal microenvironment over a 24-h period.