BIOPHARMACEUTICAL EVALUATION OF PSEUDOEPHEDRINE HYDROCHLORIDE CAPSULES CONTAINING DIFFERENT GRADES OF SODIUM ALGINATE

In the study described here hard gelatin capsules containing pseudoeph edrine hydrochloride and different grades of sodium alginate were prep ared in order to obtain prolonged-release formulations. Evaluation was carried out by means of dissolution studies at three pH levels, 1.2, 4.4 and 7.2. Penetration of the dissolution medium into the capsule wa s followed by means of photographs. Bioavailabilities of the products were assessed in man. At pH 1.2 there was no difference between the fo rmulations. At pH 7.2 release rates correlated with the viscosity grad e of sodium alginate. The drug release mechanism could be explained on the basis of the photographs. The bioavailability tests confirmed tha t capsules containing high viscosity grades of alginate led to slow re lease formulations (t(max) at 6.5 h) without any loss of amount of dru g absorbed. It was concluded that the pseudoephedrine formulations, wh ich are very simple to make, may be worth consideration in drug therap y.