Cyclodextrin Complexation as a Way of Increasing the Aqueous Solubility and Stability of Carvedilol

Abstract

We studied the effect of several CDs on carvedilol’s solubility and chemical stability in various aqueous media. Our present results show that it is possible to achieve a carvedilol concentration of 5 mg/mL (12.3 mM) in the presence of 5 eq of γCD or RAMEB in an aqueous medium with an acceptable acid pH (between 3.5 and 4.7). Carvedilol formed 1:1 inclusion complexes but those with RAMEB appear to be stronger (K = 317 M−1 at 298 K) than that with γCD (K = 225 M−1 at 298 K). The complexation of carvedilol by RAMEB significantly increased the drug’s photochemical stability in aqueous solution. These results might constitute a first step towards the development of a novel oral formulation of carvedilol.

Keywords

• carvedilol
• cyclodextrins
• pharmaceutical solutions
• NMR
• ITC