Abstract

The present investigation was aimed at enhancing the dissolution properties of carvedilol, a poorly water-soluble drug using a combination of solid dispersion and semisolid-filled capsule. The use of lauroyl polyoxyl-6 glycerides as a carrier in a semisolid base to improve the dissolution behaviour of carvedilol was investigated. Solid dispersions containing carvedilol were prepared and percent drug content was assessed. In vitro dissolution studies, Fourier-transform infrared spectroscopy, differential scanning calorimetry and scanning electron microscopy were used to characterize solid dispersions. Semisolid-filled capsules of carvedilol were prepared using different bases, and their percent drug content and in vitro dissolution behaviour were studied. The optimized solid dispersion containing 3 parts of poloxamer and 0.2 part of Plasdone K90 with respect to 1 part of carvedilol was incorporated into an optimized semisolid base containing 20 parts of lauroyl polyoxyl-6 glycerides with respect to 1 part of carvedilol). The combination of solid dispersions and semisolid-filled capsule produced a significant increase in the rate of release of the drug. The differential scanning calorimetry thermogram of the optimized semisolid formulation did not show carvedilol peak, which suggested that carvedilol had dissolved in the base in the presence of lauroyl polyoxyl-6 glycerides. The dissolution of carvedilol was improved and the lag time of drug release was reduced in the semisolid-filled capsules in which lauroyl polyoxyl-6 glycerides was used as a carrier.