Single- and Multiple-Dose Pharmacokinetics of Once-Daily Formulations of Raltegravir

A new once-daily formulation of raltegravir, an integrase strand transfer inhibitor indicated in combination with other antiretroviral drugs for the treatment of human immunodeficiency virus-1 infection, is under development. Single-dose and steady-state pharmacokinetics of 1200 mg for 2 formulations of raltegravir were characterized in 2 open-label phase 1 studies in healthy male and female subjects aged 18 to 55 years. The new raltegravir 600-mg formulation had a higher relative bioavailability compared with the 400-mg tablets. Once absorbed, both 3 × 400-mg and 2 × 600-mg dosage forms of raltegravir exhibited similar systemic pharmacokinetics; in dictating bioavailability, differences were from increased absorption that was the result of improved in vivo disintegration/dissolution. Food had a smaller effect on the pharmacokinetics of raltegravir when given as 2 × 600-mg formulation (42% vs 73% decrease in AUC_0-last ). Steady state was generally reached in 2 days, with little to no accumulation with multiple-dose administration. Raltegravir 1200 mg was found to exhibit pharmacokinetic properties amenable for once-daily dosing and was generally well tolerated in healthy subjects after single and multiple doses. The new formulation improved the bioavailability of this Biopharmaceutics Classification System class II compound.