Pharmacodynamic testing and new validated HPLC method to assess the interchangeability between multi-source orlistat capsules.

BACKGROUND: Orlistat is an irreversible inhibitor of the lipase enzyme that prevents trigylcerides from being digested, thereby inhibiting triglyceride hydrolysis and absorption. The resultant reduced calorie uptake enables a positive effect on weight control. Systemic absorption of the drug is, therefore, not necessary for its mode of action. An alternative in vitro study (pharmacodynamic) has been introduced for this drug, as in vivo bioavailability studies are irrelevant with regard to the achievement of the product's intended purposes. OBJECTIVES: To develop a new validated high-performance liquid chromatography (HPLC) method for the analysis of orlistat and to assess the potency and equivalence of three orlistat formulations using the pharmacodynamic method as a surrogate indicator of pharmaceutical interchangeability. METHODS: A new HPLC method was developed for the analysis and for the dissolution studies of orlistat in capsules. Pancreatic lipase activity was measured for three different capsule products: Orlislim®, Slimcare®, and Xenical®, G1, G2, and the brand, respectively. Porcine pancreatic lipase and p-nitrophenyl butyrate (PNPB) were placed in a pH 7.4 reaction buffer at 37°C, and substrate hydrolysis was monitored by measuring absorbance changes at 410 nm; this was repeated on six capsules of each product. The inhibition was expressed by the concentration of product, which inhibited 50% of the activity of pancreatic lipase (IC50). RESULTS: The new analytical method was suitable for orlistat analysis. Values of IC50 from regression lines and equations were 6.14, 8.43, and 7.80 µg/mL for Orlislim®, Xenical®, and Slimcare®, respectively. CONCLUSION: Pharmacodynamic studies of lipase inhibition could be used to support in vitro dissolution, which demonstrates interchangeability between generic and branded orlistat capsules. Moreover, it could be suggested as an alternative tool to bioequivalence studies for orlistat oral products.

Formulation and bioequivalence of two Valsartan/Amlodipine immediate release tablets after a single oral administration.

The aim of this study was to formulate a film-coated Valsartan/Amlodipine (VS/AM) immediate release tablets and to evaluate their in vivo release profile. VS/AM core tablets were manufactured using dry granulation method. Opadry aqueous coating dispersion was used as film coating material. Dissolution of the film coated tablets was tested in 900 ml of 0.5% SLS media, bioequivalence of tablets was tested by comparisons against the reference brand product. The ICH guidelines were used to evaluate the stability of the obtained tablets. The coated tablets were subjected to gastric pH, and drug release was analyzed using HPLC system to evaluate the efficiency of the film coat. The coated tablets had no defects. VS/AM release met the FDA guidelines for bioequivalence studies. Statistical comparison of the main pharmacokinetic parameters showed no significant difference between test and reference. These findings suggest that aqueous film coating with Opadry system is an easy and economical approach for preparing stable film coated VS/AM tablets without compromising their in vivo drugs release.

Preparation and stability evaluation of extemporaneous oral suspension of valsartan using commercially available tablets.

The aim of this study was to develop an extemporaneous valsartan suspension (80 mg valsartan/5 mL) starting from commercial tablets (80-mg/ tablet). A high-performance liquid chromatographic system was used for the analysis and quantification of valsartan in the samples studied. Samples of valsartan suspension for analysis were prepared as reported by the validated high-performance liquid chromatographic method and the dissolution tests were performed according to the U.S. Food and Drug Administration's method. The high-performance liquid chromatographic assay indicated that the 80-mg/5-mL valsartan suspension was stable for 30 days when stored at long-term and accelerated storage conditions. Valsartan release profile showed that approximately 85% of valsartan dissolved after 10 minutes and, accordingly, the calculation of similarity factor was not necessary. It is possible for the pharmacist to crush valsartan 80-mg tablets and prepare a suspension which has dosage flexibility that can be calculated according to body-surface area, kidney, and liver functions, without affecting the chemical stability of the active ingredient nor its dissolution profile and also have a cost-effective dosage form.

Formulation and in vitro and in vivo evaluation of film-coated montelukast sodium tablets using Opadry® yellow 20A82938 on an industrial scale.

PURPOSE: The aim of this study was to formulate stable film-coated montelukast sodium (MS) tablets using Opadry(®) yellow 20A82938 (Montikast(®) tablets) and to evaluate their in vitro and in vivo release profile. METHODS: MS core tablets were manufactured using a direct compression method. Opadry yellow 20A82938 aqueous coating dispersion was used as the film-coating material. Dissolution of the film-coated tablets was tested in 900 mL of 0.5% sodium lauryl sulfate solution and the bioequivalence of the tablets was tested by comparing them with a reference formulation - Singulair(®) tablets. In vitro-in vivo correlation was evaluated. The stability of the obtained film-coated tablets was evaluated according to International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use guidelines. RESULTS: The efficiency of the film coating was determined by subjecting the coated tablets to gastric pH and drug release was analyzed using high-performance liquid chromatography. The coated tablets had no obvious defects. MS release met the study criterion of not less than 80% dissolved after 30 minutes in 0.5% sodium lauryl sulfate solution. Statistical comparison of the main pharmacokinetic parameters clearly indicated no significant difference between test and reference in any of the calculated pharmacokinetic parameters. Level A correlation between in vitro drug release and in vivo absorption was found to be satisfactory. CONCLUSION: These findings suggest that aqueous film coating with Opadry yellow 20A82938 is an easy, reproducible, and economical approach for preparing stable MS film-coated tablets without affecting the drug-release characteristics.

Formulation and bioequivalence of two valsartan tablets after a single oral administration.

The aim of this study is to assess the quality of Valzan(®) tablet (160 mg, valsartan immediate release test formulation) by comparing its pharmacokinetic parameters with Diovan(®) tablet (160 mg, valsartan reference formulation). Valzan(®) tablets were prepared according to a dry granulation method (roll compaction). To assess the bioequivalence of Valzan(®) tablets a randomized, two-way, crossover, bioequivalence study was performed in 24 healthy male volunteers. The selected volunteers were divided into two groups of 12 subjects. One group was treated with the reference formulation (Diovan(®)) and the other one with the generic Valzan(®), with a cross-over after the drug washout period of 14 days. Blood samples were collected at fixed time intervals and valsartan concentrations were determined by a validated HPLC assay method. The pharmacokinetic parameters AUC(0-48), AUC(0-∞), C(max), T(max), K(e) and T(1/2) were determined for both the tablets and were compared statistically to evaluate the bioequivalence between the two brands of valsartan, using the statistical model recommended by the FDA. The analysis of variance (ANOVA) did not show any significant difference between the two formulations and 90% confidence intervals (CI) fell within the acceptable range for bioequivalence. Based on this statistical evaluation it was concluded that the test tablets (Valzan(®)) is well formulated, since it exhibits pharmacokinetic profile comparable to the reference brand Diovan(®).