Formulation and Evaluation of Propranolol Hydrochloride-Loaded Carbopol-934P/Ethyl Cellulose Mucoadhesive Microspheres

The purpose of this research was to formulate and systemically evaluate in-vitro and in-vivo performances of mucoadhesive propranolol hydrochloride microspheres for its potential use in the treatment of hypertension, myocardial infraction and cardiac arrhythmias. Propranolol hydrochloride mucoadhesive microspheres, containing carbopol-934P as mucoadhesive polymer and ethyl cellulose as carrier polymer, were prepared by an emulsion-solvent evaporation technique. Results of preliminary trials indicated that the quantity of emulsifying agent, time for stirring, drug-to-polymers ratio, and speed of rotation affected various characteristics of microspheres. Microspheres were discrete, spherical, free-flowing and showed a good percentage of drug entrapment efficiency. An in-vitro mucoadhesive test showed that propranolol hydrochloride mucoadhesive microspheres adhered more strongly to the gastric mucous layer and could be retained in the gastrointestinal tract for an extended period of time. A 32 full factorial design was employed to study the effect of independent variables, drug-to-polymer-to-polymer ratio (propranolol hydrochloride-ethyl cellulose-carbopol-934P) (X1), and stirring speed (X2) on dependent variables, i.e. percentage of mucoadhesion, drug entrapment efficiency, particle size and t80. The best batch exhibited a high drug entrapment efficiency of 54 %; 82% mucoadhesion after 1 h and particle size of 110 µm. A sustained pattern of drug release was obtained for more than 12 h. The drug-to-polymer-to-polymer ratio had a more significant effect on the dependent variables. The morphological characteristics of the mucoadhesive microspheres were studied under a scanning electron microscope. In-vivo evaluation studies on propranolol hydrochloride mucoadhesive microspheres and propranolol hydrochloride powder were performed on normal healthy rabbits. The results showed a sustained anti-hypertensive effect over a longer period of time in case of mucoadhesive microspheres, compared to the powder. In conclusion, the prolonged gastrointestinal residence time and slow release of propranolol hydrochloride resulting from the mucoadhesive microspheres, could contribute to the provision of a sustained anti-hypertensive effect.