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Related Articles Pharmacokinetics and bioequivalence study of three oral formulations of valsartan 160 mg: a single-dose, randomized, open-label, three-period crossover comparison in healthy Indian male volunteers. Clin Ther. 2010 Mar;32(3):588-96 Authors: Iqbal M, Khuroo A, Batolar LS, Tandon M, Monif T, Sharma PL BACKGROUND: Valsartan is a selective angiotensin II type 1 receptor blocker indicated for the treatment of hypertension. Although the bioavailability and pharmacokinetic properties of valsartan have been well characterized, a literature search did not identify any reports concerning the bioavailability of valsartan in the Indian population. OBJECTIVE: This study was undertaken to compare the pharmacokinetic properties of 2 branded generic valsartan formulations (tests A and B) with a branded innovator product (reference) in healthy Indian male subjects. METHODS: This single-dose, randomized, open-label, 3-period crossover study compared the pharmacokinetic properties of 3 marketed brands of valsartan 160-mg tablets in healthy Indian male volunteers aged 18 to 45 years under fasting conditions. Subjects were assigned to receive, in randomized order, a single oral dose of 1 of 2 test formulations (A or B) or a reference formulation of valsartan 160 mg. Each study period was separated by a 5-day washout period. Blood samples were collected at prespecified times over a period of 24 hours after administration. An HPLC method was used for the estimation of plasma valsartan concentrations. A noncompartmental method was employed to determine the pharmacokinetic properties (C(max), T(max), AUC(0-t), AUC(0-infinity), and t(1/2)) to test for bioequivalence. The predetermined regulatory range of 90% CI for bioequivalence was 80% to 125%. Tolerability was assessed using physical examination, including vital sign measurement, and direct questioning. RESULTS: The study was conducted in 18 subjects (mean age, 24.8 years; weight, 54.5 kg; and height, 164.67 cm). For test formulation A versus the reference formulation, the 90% CIs of the least squares mean test/reference ratios of C(max), AUC(0-t), and AUC(0-infinity) were 81.18% to 115.74%, 77.27% to 108.75%, and 79.32% to 108.70%, respectively. For test B versus reference, the corresponding values were 84.69% to 120.73%, 83.72% to 117.84%, and 84.40% to 115.67%. No adverse events were found or reported by subjects throughout the study. CONCLUSIONS: In this single-dose study in a small sample of healthy Indian male subjects, test formulation B of valsartan 160 mg was considered bioequivalent to the reference formulation as per predetermined regulatory criteria, whereas test formulation A was not. All 3 formulations were well tolerated. PMID: 20399995 [PubMed - indexed for MEDLINE]

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Related Articles Bioavailability of generic ritonavir and lopinavir/ritonavir tablet products in a dog model. J Pharm Sci. 2010 Feb;99(2):626-31 Authors: Garren KW, Rahim S, Marsh K, Morris JB In this study, we explored the bioavailability in dogs and chemical potency of generic ritonavir and lopinavir/ritonavir tablet products manufactured by various pharmaceutical companies. Chemical potency of the products was examined by HPLC quantitation of ritonavir and lopinavir. Using a dog model, we determined point estimates for C(max) and AUC of ritonavir and lopinavir/ritonavir for eight generic products compared to Abbott’s Norvir capsule and Kaletra tablet. Chemical potencies ranged from 79.0% to 104.6%. Point estimates for AUC in the generic tablet products ranged from 0.01 to 1.11, indicating that the relative bioavailability of these formulations was in the range of 1-111% compared to the branded products. This study showed significant variability in bioavailability in a dog model amongst generic tablet products containing the protease inhibitors ritonavir or lopinavir/ritonavir. The chemical potency of the generic products was not indicative of the plasma levels of ritonavir or lopinavir that were achieved. These results reinforce the need for human bioequivalence testing of generic products containing ritonavir or lopinavir/ritonavir to assure that efficacy in patients is not compromised prior to these products being made available to patients. Procurement policies of funding agencies should require such quality assurance processes. PMID: 19230020 [PubMed - indexed for MEDLINE]

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