Abstract

The purpose of this research was to prepare floating microballoons consisting of (i) calcium silicate as porous carrier; (ii) propranolol hydrochloride (PRH), an oral anti-hypertensive agent; and (iii) Eudragit S as polymer, by solvent evaporation method and to evaluate their gastro-retentive and controlled release properties. The effect of various formulation and process variables on the particle morphology, micromeritic properties, in-vitro floating behavior, percentage drug entrapment, and in-vitro drug release was studied. The gamma scintigraphy of the optimized formulation was performed in albino rabbits to monitor the transit of floating microballoons in the gastrointestinal tract. The propranolol hydrochloride-loaded optimized formulation was orally administered to albino rabbits, and blood samples collected were used to determine pharmacokinetic parameters of propranolol hydrochloride from floating microballoons. The microballoons were found to be regular in shape and highly porous. Microballoons formulation CS4, containing 200 mg calcium silicate showed the best floating ability (89 ± 4% buoyancy) in simulated gastric fluid as compared with other formulations. Release pattern of propranolol hydrochloride in simulated gastric fluid from all floating microballoons followed Higuchi matrix model and Peppas-Korsmeyer model. Prolonged gastric residence time of over 6 h was achieved in all rabbits for calcium silicate based floating microballoons of propranolol hydrochloride. The enhanced elimination half life observed after pharmacokinetic investigations in the present study is due to the floating nature of the designed formulations.

Key words: Propranolol hydrochloride, calcium silicate, gastroretentive floating drug delivery, microballoons, gamma scintigraphy.