Raltegravir 400 mg · Tablets

Raltegravir is an HIV-1 antiviral drug [see Microbiology ( 12.4)] .

Absorption — Raltegravir, given 400 mg twice daily, is absorbed with a T maxof approximately 3 hours postdose in the fasted state in healthy subjects. Raltegravir 1200 mg once daily is rapidly absorbed with median T maxof ~1.5 to 2 hours in the fasted state.

Raltegravir increases dose proportionally (AUC and C max) or slightly less than dose proportionally (C 12hr) over the dose range 100 mg to 1600 mg.

The absolute bioavailability of raltegravir has not been established. The chewable tablet and oral suspension have higher oral bioavailability compared to the 400 mg film-coated tablet.

Relative to the raltegravir 400 mg formulation, the raltegravir 600 mg formulation has higher relative bioavailability.

Steady-state is generally reached in 2 days, with little to no accumulation with multiple dose administration for the 400 mg twice daily and 1200 once daily formulation.

Effect of Food on Oral Absorption — The food effect of various formulations are presented in Table 12.

Distribution — Raltegravir is approximately 83% bound to human plasma protein over the concentration range of 2 to 10 µM.

In one study of HIV-1 infected subjects who received raltegravir 400 mg twice daily, raltegravir was measured in the cerebrospinal fluid. In the study (n=18), the median cerebrospinal fluid concentration was 5.8% (range 1 to 53.5%) of the corresponding plasma concentration. This median proportion was approximately 3-fold lower than the free fraction of raltegravir in plasma. The clinical relevance of this finding is unknown.

Metabolism and Excretion — The apparent terminal half-life of raltegravir is approximately 9 hours, with a shorter α-phase half-life (~1 hour) accounting for much of the AUC. Following administration of an oral dose of radiolabeled raltegravir, approximately 51 and 32% of the dose was excreted in feces and urine, respectively. In feces, only raltegravir was present, most of which is likely derived from hydrolysis of raltegravir-glucuronide secreted in bile as observed in preclinical species. Two components, namely raltegravir and raltegravir-glucuronide, were detected in urine and accounted for approximately 9 and 23% of the dose, respectively. The major circulating entity was raltegravir and represented approximately 70% of the total radioactivity; the remaining radioactivity in plasma was accounted for by raltegravir-glucuronide. The major mechanism of clearance of raltegravir in humans is UGT1A1-mediated glucuronidation.

Raltegravir — Two pediatric formulations were evaluated in healthy adult volunteers, where the chewable tablet and oral suspension were compared to the 400 mg tablet. The chewable tablet and oral suspension demonstrated higher oral bioavailability, thus higher AUC, compared to the 400 mg tablet. In the same study, the oral suspension resulted in higher oral bioavailability compared to the chewable tablet. These observations resulted in proposed pediatric doses targeting 6 mg/kg/dose for the chewable tablets and oral suspension. As displayed in Table 14, the doses recommended for HIV-infected infants, children and adolescents 4 weeks to 18 years of age [see Dosage and Administration (2.3)] resulted in a pharmacokinetic profile of raltegravir similar to that observed in adults receiving 400 mg twice daily.

Overall, dosing in pediatric patients achieved exposures (C trough) above 45 nM in the majority of subjects, but some differences in exposures between formulations were observed. Pediatric patients above 25 kg administered the chewable tablets had lower trough concentrations (113 nM) compared to pediatric patients above 25 kg administered the 400 mg tablet formulation (233 nM) [see Clinical Studies (14.4)] . As a result, the 400 mg film-coated tablet is the recommended dose in patients weighing at least 25 kg; however, the chewable tablet offers an alternative regimen in patients weighing at least 25 kg who are unable to swallow the film-coated tablet [see Dosage and Administration (2.3)] . In addition, pediatric patients weighing 11 to 25 kg who were administered the chewable tablets had the lowest trough concentrations (82 nM) compared to all other pediatric subgroups.