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Ezetimibe is a lipid-lowering compound that selectively inhibits the absorption of cholesterol and related phytosterols from the intestine. As ezetimibe is almost insoluble in water, its bioavailability is too low to be detected. Thus, the objective of this study was to improve the solubility and dissolution rate of ezetimibe by preparing drug nanocrystals utilizing ball milling, high speed homogenization techniques. Pluronic F127 was chosen as a surface modifier to stabilize the nanocrystal formulations. Nanocrystal formulations of ezetimibe were prepared by using ball milling and high speed homogenization techniques. Additionally, the physicochemical characteristics of ezetimibe and nanocrystal formulations were determined by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), X-ray analysis and particle size analysis. Tablets were prepared containing ezetimibe nanocrystals formed by high speed homogenization (ultrasonic) and ball milling according to the results of particle size measurements and in vitro dissolution rates of the nanocrystal formulations. As a result of these experiments, it was found that the dissolution rate of the nanocrystal formulations increased and although tablet formulations which did not contain any solubilizing agent like sodium lauryl sulfate (SDS), the dissolution profile of these formulations were found similar to the commercial product.

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The purpose of this study was to evaluate the similarity of dissolution and permeability properties of commercially available immediate-release metformin hydrochloride (MH) tablets (1000 mg strength) including five generic products obtained from the Turkish drug market (tablets A-E) and two reference products (obtained from the Turkish and European markets). In vitro dissolution studies were conducted in accordance with the MH tablet monograph in the USP (1000 mL, 75 rpm) and with the BCS-based biowaiver guidance in three different media (pH 1.2, pH 4.5, and pH 6.8; 900 mL, 50 rpm). The apparent permeability of MH in all tablets and raw MH was determined in Caco-2 cells. Dissolution studies revealed that neither the generics (except generic tablet B) nor the reference tablets fulfilled the criteria for very rapid dissolution. Although the dissolution profiles of the reference tablets were similar (f 2 > 50), none of the generic tablets were similar to either of the reference tablets. Permeability of MH for all reference and generic tablet formulations was similar to that of raw MH (p > 0.05). In contrast, a significant difference in permeability was observed between the two reference tablets (p < 0.05), and only one generic tablet (A) had permeability similar to both reference tablets. As MH has low permeability, potential alterations in permeability due to the dosage form can affect its bioavailability. The results of this study indicate that immediate-release MH tablets do not meet the criteria for very rapid dissolution for the BCS-based biowaiver.