Stereoselective dissolution of propranolol hydrochloride from hydroxypropyl methylcellulose matrices.

Since many chiral pharmaceutical excipients, such as cellulose polymers and cyclodextrins, are used as stationary phases for the separation of enantiomers by high performance liquid chromatography (HPLC), it is hypothesized that one enantiomer of a chiral drug will be released faster than the other from a pharmaceutical formulation containing a racemic drug and a chiral excipient. The mechanism of such an event may arise from preferential intermolecular interaction between the chiral excipient and one of the enantiomers. To test this hypothesis, the release of the enantiomers of propranolol hydrochloride into water from formulations containing the chiral excipients, hydroxypropyl methylcellulose (HPMC) or beta-cyclodextrin, was investigated by stereospecific HPLC analysis of the dissolved concentrations of each of the enantiomers from the formulations. The release of the enantiomers of propranolol hydrochloride from the formulations containing HPMC, although variable, was found to be stereoselective. However, the release of propranolol hydrochloride enantiomers from the beta-cyclodextrin complex was found to be non-stereoselective.