A pharmacokinetic and bioequivalence study of Contiflo ICON 400 µg tablets in healthy Indian subjects.

INTRODUCTION: Tamsulosin, an alpha1 adrenoceptor blocking agent, exhibits selectivity for alpha1 receptors in human prostate. Blockade of these adrenoceptors can cause smooth muscles in the bladder neck and prostate to relax, resulting in an improvement in urine flow rate and a reduction in symptoms of benign prostatic hypertrophy. A new formulation Contiflo ICON 400 µg has been developed by Ranbaxy Laboratories Limited, India similar to Flomaxtra XL 400 µg of Astellas Pharma Limited, United Kingdom. This product is specifically designed to achieve a more consistent plasma concentration over a period of 24-h, a lower maximum plasma concentration (Cmax) and an independence of pharmacokinetics (PKs) on food intake. METHODS: The objective of the present study was to evaluate the pharmacokinetics and bioequivalence of the new formulation Contiflo ICON 400 µg of Ranbaxy Laboratories Limited, India and Flomaxtra XL 400 µg prolonged release tablets (containing tamsulosin hydrochloride prolonged release 400 µg) of Astellas Pharma Limited, United Kingdom. Study was conducted as an open label, balanced, randomized, two-treatment, two-period, two-sequence, cross over, single-dose bioequivalence study in 32 adult male human subjects under fed conditions. The mean (range) age, weight and height of the study subjects were 27.03 years (19 - 40 years), 57.19 kg (48 - 72 kg) and 166.81 cm (154 - 181 cm) respectively. Blood samples were collected at pre-dose and at 0.5, 1, 2, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 8, 9, 10, 12, 16, 20, 24, 36, 48, 72, and 96 h post dose in each period. Plasma samples were analyzed for tamsulosin by using validated liquid chromatographic mass spectrometry (LC-MS/MS) method. RESULTS: The Mean ± SD of pharmacokinetic parameters tmax, Cmax, AUC24, AUClast and AUCinf for Tamsulosin were 11.741 ± 4.7201 and 12.155 ± 6.3077 h, 10.7614 ± 4.76709 and 10.4954 ± 5.08979 ng/ml, 171.4674 ± 77.39695 and 160.6738 ± 77.98628 ng.h/ml, 262.7771 ± 150.21432 and 250.6854 ± 156.75581 ng.h/ml, 280.0702 ± 152.14253 and 273.5078 ± 156.85910 ng.h/ml for test and reference formulations respectively. The ratios of least square means and the 90% confidence interval of log transformed pharmacokinetic parameter Cmax, AUC24, AUClast and AUCinf were within 80 - 125% acceptance range. CONCLUSION: In conclusion, Contiflo ICON 400 µg tablets developed by Ranbaxy Laboratories Limited is bioequivalent to the reference formulation in healthy adult male volunteers under fed condition.

Pharmacodynamic equivalence of two orlistat capsule formulations in healthy volunteers under fed conditions.

OBJECTIVE: Orlistat is a reversible lipase inhibitor for obesity management. Orlistat exerts its pharmacological activity in the lumen of the stomach and small intestine by binding with the active site of gastric and pancreatic lipases, with the consequent inhibition of the systemic absorption of dietary fat. The undigested triglycerides are not absorbed, resulting in caloric deficit and positive effect in weight control. The objective of this study was to assess, using fat excreted in feces, the pharmacodynamic equivalence of orlistat when administered as generic and innovator capsule formulations. MATERIALS AND METHODS: A total of 18 healthy volunteers (12 males and 6 females) followed a 5-day run-in diet period in order to become accustomed to a high fat diet. Subjects were then randomized to receive under fed conditions oral doses of orlistat (120 mg) 3 times daily for 10 consecutive days as the generic (Ranbaxy Laboratories) or innovator (Xenical, Roche Laboratories, Nutley, NJ, USA) capsule formulations. Subjects followed a standardized diet (2,500 kcal/day, 30% as fat) for the entire study. Feces were collected over the last 2 days of the run-in period (baseline) and over the last 5 days of the 2 treatment periods. The amount of fat in meals and feces was assayed with a limit of detection of 0.1 and 0.2%, respectively. Fecal fat excretion over 24 hours (FFE(24), calculated as the percentage of amount of fat excreted in feces relative to the amount of fat ingested) was used as a pharmacodynamic endpoint to assess the therapeutic equivalence between the 2 orlistat formulations. An analysis of variance (ANOVA) was performed on FFE(24) parameters. RESULTS: Mean FFE(24) values at baseline and after repeated oral administrations of the generic and innovator formulations of orlistat were 6.48, 20.0 and 19.6%, respectively. The ratio of least-squares means (LSM) of FFE(24) of the generic to the innovator formulation was 99.1%, with 90% confidence intervals of 83.8 -114.5%. Adverse events for the generic and innovator products were similar in nature and frequency. CONCLUSION: Mean FFE(24) values were used as pharmacodynamic endpoints to assess equivalence between 2 formulations of orlistat. Results from this study suggest that pharmacodynamics of the generic capsule formulation of orlistat were similar to the marketed capsule formulation based on FFE(24) values.

A bioequivalence study comparing two formulations of lopinavir/ritonavir capsules.

This investigation was carried out to evaluate the bioavailability of a new single fixed-dose combination formulation of lopinavir and ritonavir, relative to reference product, Kaletra (133.3 mg lopinavir/33.3 mg ritonavir) capsules, manufactured by Abbott Laboratories, Chicago, IL, USA. The bioavailability study was carried out on 72 healthy male and female volunteers who received a single dose of 3 capsules (133.3 mg lopinavir/33.3 mg ritonavir) of the test (T) and the reference (R) products in the fasting state, in a randomized, balanced, 2-way crossover design. After dosing, serial blood samples were collected for a period of 72 hours. Plasma harvested from blood was analyzed for lopinavir and ritonavir by a sensitive and validated simultaneous liquid-chromatographic and mass-spectrometric (LC-MS/MS) assay. Mean oral clearance (Cl/F) values of the FDC were 4.92 and 23.54 l/h for lopinavir and ritonavir, respectively, the maximum plasma concentrations (C(max)), area under the plasma concentration-time curve up to the last measurable concentration (AUC(0-t)), and to infinity (AUC(0-infinity)), were analyzed statistically under the assumption of a multiplicative model. The time to maximum concentration (t(max)) was analyzed assuming an additive model. The parametric confidence intervals (90%) were calculated by Schuirmann's two 1-sided t-test criteria. It was found that the test/reference (T/R) ratios for the pharmacokinetic parameters AUC(0-t), AUC(0-infinity) and C(max) (after initial log transformation) were well within the bioequivalence acceptance range of 80-125% as per international regulatory guidelines. Therefore, the two formulations were considered to be bioequivalent [Food and Drug Administration 2003].

Pharmacokinetics of lamivudine, zidovudine, and nevirapine administered as a fixed-dose combination formulation versus coadministration of the individual products.

The pharmacokinetics of 150 mg lamivudine, 300 mg zidovudine, and 200 mg nevirapine were assessed following single oral administration of a fixed-dose combination tablet and coadministration of the separate innovator products in healthy male subjects (n = 64) under fasting conditions in an open-label, randomized, 2-way crossover study. Multiple blood samples were collected up to 72 hours and plasma concentrations of antiretrovirals were assayed using liquid chromatography/tandem mass spectrometry methods. Pharmacokinetic parameters were calculated using noncompartmental methods, and bioequivalence was assessed using an analysis of variance model. The ratio of the least squares mean (fixed-dose combination to individual products) and 90% confidence intervals of AUC(0-t), AUC(0-infinity), and C(max) for lamivudine, zidovudine, and nevirapine were all within 80.0% to 125.0%, suggesting a similar rate and extent of antiretroviral exposure in the bloodstream. Mean oral clearance (CL/F) values of lamivudine, zidovudine, and nevirapine for the fixed-dose combination were 23.7, 127, and 1.65 L/h, respectively. The fixed-dose combination and individual products were equally safe and well tolerated, with only a few subjects experiencing drug-related adverse events. The current fixed-dose combination of lamivudine, zidovudine, and nevirapine is expected to provide a similar efficacy/safety profile as coadministration of the individual products, a better adherence to treatment, and considerable cost savings in the treatment of HIV.