Preparation and characterisation of sustained-release ibuprofen-cetostearyl alcohol spheres

Abstract

Spherical ibuprofen-cetostearyl alcohol matrices were prepared using a technique involving melting and suspension of drug-containing cetostearyl alcohol in an aqueous medium. The resulting emulsion was cooled under rapid stirring to produce the spheres. Release of ibuprofen from the pellets was modelled using standard drug-release equations. Numerical fits indicate that the contracting sphere model (the cube root equation) was the most appropriate one for describing the complete release profiles. Within the range of drug release rates of 20–80% the model was indistinguishable from the Higuchi square root of time model. Using the slopes from the latter model, the effects of drug loading, particle size and stirring speed during the preparation of the pellets were investigated. Differential scanning calorimetry was used to explain some unusual observations and it was shown that eutectic formation between ibuprofen and cetostearyl alcohol may account for the unusually high ibuprofen release rates from pellets containing ibuprofen, at levels close to the eutectic composition.