Study of the solubility, photostability and structure of inclusion complexes of carvedilol with β-cyclodextrin and (2-hydroxypropyl)-β-cyclodextrin

Carvedilol is one of the most effective antihypertensive drugs used in the treatment of congestive heart failure. A major disadvantage of this pharmaceutical active substance is its limited solubility in water, gastric and intestinal fluids. One way to overcome this problem is the preparation of inclusion complexes. The aim of this study was to prepare the inclusion complexes of carvedilol with beta-cyclodextrin (beta-CD) and (2-hydroxypropyl)-beta-cyclodextrin (HP-beta-CD) and to investigate their physical properties. The formation of inclusion complexes with beta-CD and HP-beta-CD was confirmed using FTIR, H-1-NMR and XRD methods. Phase solubility studies indicate the formation of inclusion complexes in 1:2 molar ratio and the increase of carvedilol solubility. The stability constant (beta (2)) was found to be 3.4 x 10(4) and 5.1 x 10(4) M-2 for inclusion complexes of carvedilol:beta-CD and carvedilol:HP-beta-CD, respectively. Photostability of carvedilol was increased after preparation of inclusion complexes with beta-CD and HP-beta-CD. Based on the results of this study, it can be concluded that the prepared complexes of carvedilol improve the solubility and stability of carvedilol and give it an advantage to be applied for the design of new pharmaceutical formulations.