FACTORS AFFECTING DRUG RELEASE FROM A PELLET SYSTEM COATED WITH AN AQUEOUS COLLOIDAL DISPERSION

The formulation of sustained-release pellets of dextromethorphan hydrobromide is described. The system used consisted of drug-coated sugar spheres which were then overcoated with the rate-controlling membrane. The membrane was produced by spray-coating with an aqueous dispersion of ethylcellulose containing hydroxypropyl methylcellulose. It is shown that adequate post-coating conditioning is important to ensure consistency of release rates. Conditioning at 60-degrees-C for at least 1 h is necessary in order to ensure that the formulations produced show no ageing effects in release rates. Drug release could be made pH-independent by a choice of proper formulation.