Influence of the acid type on the physical and drug liberation properties of chitosan-gelatin sponges

The influence of acid type used to dissolve chitosan on the resulting spong e physical properties, and their consequent effect on the drug liberation w ere investigated. Chitosan was dissolved in different acid solutions and ch itosan-gelatin sponges were produced by frothing up the polymer solution an d then freeze-drying the foam. Prednisolone was used as a model drug. Using tartaric or citric acid resulted in instable, soft, elastic and disintegra ting sponges with fast drug release. Elastic but harder sponges from stable foams were obtained when hydrochloric or lactic acid were used. The use of acetic or formic acid enabled the production of stable foams, soft and ela stic sponges and a slow drug release. The rate of drug release was decrease d by crosslinking the polymers with glutaraldehyde, but only if acetic, for mic or acetic acid were used. Therefore, it is possible to manipulate the m echanical properties and the drug liberation rate by using different acids to dissolve chitosan. (C) 2000 Elsevier Science B.V. All rights reserved.