Relationship between gum content and half-life of soluble β blockers from hydrophilic matrix tablets

Abstract

The effect of the ratio of the amount of total gum to drug and also the ratio between the gums, i.e. hydroxypropylmethylcellulose (HPMC) and sodium carboxymethylcellulose (NaMC), on the release rate of drug was studied by taking 4 soluble β-adrenergic blockers, viz. propranolol hydrochloride, alprenolol hydrochloride, metoprolol tartrate and oxprenolol hydrochloride, as model drugs. A linear relationship existed in a particular range between the half-life of the tablet (time to release 50% of drug in vitro) and the ratio of total gum content to drug. This correlation holds good for these soluble β-blockers when HPMC alone or when a fixed ratio of HPMC and NaCMC was used as matrix materials. This relationship will be of immense help in optimising the composition of sustained release formulations.