Factors affecting the release of papaverine from spheres.

The effect of selected carriers and auxiliary hydrophilic agents on the papaverine loading and its release from spheres prepared by instilling viscous liquids into a 1% solution of calcium chloride in ethanol was studied. The most favourable loading of papaverine in potato starch, sodium alginate and sodium carboxymethylcellulose spheres was 97.4%, 95.7% and 91% respectively, and it depended on the presence of auxiliary hydrophilic agents such as polyethylene glycol 1500, polyethylene glycol 4000, glyceryl monostearate and sorbitan tristearate (Tween 65). The drug's release from spheres was diffusion controlled in accordance with the Higuchi model for the release of 80-95% of contents. It was concluded that the release rate constants depended on the drug-carrier-hydrophilic agent composition.