Evaluation and correlation of the physicochemical properties of carvedilol

Carvedilol is an antihypertensive drug with non-selective blockade (moderate selectivity for 1 and 2 adrenoceptors) and vasodilating properties due to receptor blockade. Its molecule has one chiral centre; therefore, the drug has two enantiomers. Furthermore, it presents different polymorphs depending on the synthesis route and crystallization procedure. Carvedilol is a weak base that is substantially insoluble in water, acidic solutions, and gastric and intestinal fluids; it is classified as a Class II drug in the Biopharmaceutical Classification System. The solubility of carvedilol varies according to the solvent pH. This study aimed to evaluate and correlate the physicochemical and processability properties of carvedilol. Samples of the active ingredient from three different manufacturers were characterized according to their flowability, particle size and apparent density and using microscopy, differential scanning calorimetry (DSC), thermogravimetric analysis, X-ray diffraction, Fourier transform infrared spectroscopy, intrinsic dissolution and powder dissolution tests. It was determined that the tested samples presented the same polymorphic form, did not present good flowability, and presented different particle size distributions. The tests to evaluate flowability and compressibility were shown to be discriminative, and slight differences among the samples were noted.