MACROMOLECULAR DRUG CONJUGATES PROPRANOLOL-CATION EXCHANGERS DRUG-DELIVERY SYSTEMS

The paper discusses the conjugates formation between propranolol - bas ic drug and the synthetic or polysaccharide-based cation exchangers, a s well as their release behaviour, with the aim to evaluate the effect ivness of hydrophylic polysaccharidic ion exchangers as carriers for p ropranolol sustained release. It was observed that, whereas hydrophyli c natural cation exchangers (sulfopropyl crosslinked dextran, sulfoeth yl crosslinked dextran, crosslinked dextran sulfate) lead quickly to p ropranolol ionic conjugates, with a non-diffusion controlled rate, the hydrophobic styrene-divinylbenzene sulfonic cation exchangers adsorb the drug by ionic exchange, at rates depending on the crosslinking deg rees and particle size. The same differences were observed at release behaviour, the propranolol being released in a larger amount and with a higher rate from the polysaccharidic cation exchangers than the synt hetic ones. Langmuir and Freundlich isotherms have been plotted and La ngmuir's constants calculated.