Abstract

Propranolol hydrochloride was formulated as oral controlled release matrix tablets using hydrophilic polymer such as hydroxypropyl methylcellulose K4M along with electrolytes. In this work a new attempt was made for in situ interactions between drug and electrolytes are devised to control the release of highly water-soluble drugs from oral hydrophilic monolithic systems. Electrolytes such as calcium carbonate, magnesium carbonate, sodium bicarbonate and sodium carbonate were used at different concentrations (5 to 100 mg per tablet) in various formulations, while drug and polymer concentrations were maintained constantly at 1:2 level in all the formulations. These electrolytes were used to monitor matrix swelling and gel properties. Electrolytes at higher concentrations (75 to 100 mg per tablet) exhibited greater inhibition in drug release from the matrix and at low concentrations (5 to 50 mg per tablet) these were accounted for controlled release of the drug. The results indicated that the drug released at a controlled rate which is due to differential swelling rate, matrix stiffening and provides a uniform gel layer. These findings indicated that the swelling and gel formation in the presence of ionisable species with in the hydrophilic matrices provide an attractive alternative for controlled drug delivery from a simple monolithic system.