STUDIES ON PECTIN FORMULATIONS FOR COLONIC DRUG-DELIVERY

An investigation has been undertaken to assess, in vitro, the potentia l of several pectin formulations as colonic drug delivery systems. Exp eriments were conducted on the release of model compounds from matrix tablets under conditions pertaining to those in vivo. The monitoring o f release gives a sensitive indication of the behaviour of the pectin under the different conditions. The type of pectin, the presence of ca lcium and the solubility of the calcium salt all influence release. Ad ditionally, pectins with a low degree of methoxylation were more susce ptible to enzymic breakdown. Calcium enhanced the enzymic activity. Rh eological studies indicated that gel strength was a factor in determin ing release. These findings suggest that either a high methoxy pectin formulation or a low methoxy pectin with a carefully controlled amount of calcium should maximise colonic specificity by providing optimal p rotection of a drug during its transit to the colon and a high suscept ibility to enzymic attack.