Formulation and preparation of controlled release pellets of salbutamol by the air suspension technique

A controlled release preparation of salbutamol may improve patient compliance, minimise side effects and be valuable in the treatment of nocturnal asthma by extending drug action throughout the night. The aim of the study was therefore to formulate a controlled release pellet preparation of salbutamol via the air suspension technique. The study established that curing for 24 h at 38 +/- 0.5 degrees C was necessary for homogeneous film coats of Eudragit RS30D and hence stable drug release characteristics. Pellets coated with 6% Eudragit RS30D (polymer), 12.5% triethyl citrate (plasticiser) and 0.5% magnesium stearate (antitackiness agent) displayed desirable controlled drug release characteristics over the 8 h testing period. The manufacturing conditions employed in the study were shown to be reproducible thus ensuring reproducibility of drug release characteristics between batches of salbutamol controlled release pellets. Short term stability testing on the newly formulated pellets indicated no significant change in drug release characteristics relative to the initial drug release data when stored for 8 weeks at room temperature 20 +/- 2 degrees C or 37 degrees C with 80% Relative Humidity or at low temperature (5 +/- 1 degrees C). However, pellets stored at 40 degrees C showed a slower in-vitro drug release after 8 weeks of storage and therefore failed to maintain their initial drug release profile.