BACKGROUND:Rosiglitazone is an insulin-sensitizing oral agent in the thiazolidinedione class used to treat patients with type 2 diabetes mellitus. It binds to peroxisome proliferator-activated receptor gamma in liver, muscle, and adipose tissue. Ranitidine, a histamine2-receptor antagonist, may be prescribed for patients with type 2 diabetes and esophageal symptoms such as heartburn. By raising gastrointestinal pH levels, ranitidine may affect the bioavailability of coadministered drugs. OBJECTIVES: This article presents the absolute bioavailability of rosiglitazone, as well as the effects of ranitidine on the pharmacokinetics of rosiglitazone. METHODS:Healthy men were enrolled in a randomized, open-label, 4-period, period-balanced crossover study of rosiglitazone and ranitidine. All individuals received each of 4 regimens successively, separated by a 4-day washout period: a single IV dose of rosiglitazone 2 mg administered alone over 1 hour; a single IV dose of rosiglitazone 2 mg administered over 1 hour on the fourth day of treatment with oral ranitidine 150 mg given every 12 hours; a single oral dose of rosiglitazone 4 mg alone; and a single oral dose of rosiglitazone 4 mg on the fourth day of treatment with oral ranitidine 150 mg given every 12 hours. The primary end point was dose-normalized area under the plasma concentration-time curve from time 0 to infinity (AUC(0-infinity)). Maximum observed plasma concentration (Cmax), the time at which Cmax occurred (Tmax), plasma clearance (CL), steady-state volume of distribution (Vss), and terminal elimination half-life (t 1/2) were also assessed. RESULTS:Twelve individuals were enrolled. The absolute bioavailability of rosiglitazone was 99%. For AUC(0-infinity), the point estimate and the associated 95% CI for the ratio of ranitidine + IV rosiglitazone to IV rosiglitazone alone was 1.02 (range, 0.88-1.20). With oral rosiglitazone, the AUC(0-infinity) point estimate (95% CI) for the ratio of ranitidine + rosiglitazone to rosiglitazone alone was 0.99 (range, 0.85-1.16). Cmax, Tmax, t 1/2, Vss and CL of rosiglitazone, whether administered orally or intravenously, were unaffected by ranitidine. Oral and IV rosiglitazone were associated with a favorable safety profile and were well tolerated with or without concurrent ranitidine treatment. CONCLUSIONS: In this study of 12 healthy adult male volunteers, the absolute bioavailability of rosiglitazone was 99%, and the oral and IV single-dose pharmacokinetics of rosiglitazone were unaltered by concurrent treatment with ranitidine.
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BACKGROUND:Rosiglitazone is an insulin-sensitizing oral agent in the thiazolidinedione class used to treat patients with type 2 diabetes mellitus. It binds to peroxisome proliferator-activated receptor gamma in liver, muscle, and adipose tissue. Ranitidine, a histamine2-receptor antagonist, may be prescribed for patients with type 2 diabetes and esophageal symptoms such as heartburn. By raising gastrointestinal pH levels, ranitidine may affect the bioavailability of coadministered drugs. OBJECTIVES: This article presents the absolute bioavailability of rosiglitazone, as well as the effects of ranitidine on the pharmacokinetics of rosiglitazone. METHODS: Healthy men were enrolled in a randomized, open-label, 4-period, period-balanced crossover study of rosiglitazone and ranitidine. All individuals received each of 4 regimens successively, separated by a 4-day washout period: a single IV dose of rosiglitazone 2 mg administered alone over 1 hour; a single IV dose of rosiglitazone 2 mg administered over 1 hour on the fourth day of treatment with oral ranitidine 150 mg given every 12 hours; a single oral dose of rosiglitazone 4 mg alone; and a single oral dose of rosiglitazone 4 mg on the fourth day of treatment with oral ranitidine 150 mg given every 12 hours. The primary end point was dose-normalized area under the plasma concentration-time curve from time 0 to infinity (AUC(0-infinity)). Maximum observed plasma concentration (Cmax), the time at which Cmax occurred (Tmax), plasma clearance (CL), steady-state volume of distribution (Vss), and terminal elimination half-life (t 1/2) were also assessed. RESULTS: Twelve individuals were enrolled. The absolute bioavailability of rosiglitazone was 99%. For AUC(0-infinity), the point estimate and the associated 95% CI for the ratio of ranitidine + IV rosiglitazone to IV rosiglitazone alone was 1.02 (range, 0.88-1.20). With oral rosiglitazone, the AUC(0-infinity) point estimate (95% CI) for the ratio of ranitidine + rosiglitazone to rosiglitazone alone was 0.99 (range, 0.85-1.16). Cmax, Tmax, t 1/2, Vss and CL of rosiglitazone, whether administered orally or intravenously, were unaffected by ranitidine. Oral and IV rosiglitazone were associated with a favorable safety profile and were well tolerated with or without concurrent ranitidine treatment. CONCLUSIONS: In this study of 12 healthy adult male volunteers, the absolute bioavailability of rosiglitazone was 99%, and the oral and IV single-dose pharmacokinetics of rosiglitazone were unaltered by concurrent treatment with ranitidine.