Biomedical silicone elastomers as carriers for controlled release

Biomedical silicone elastomers have been studied for their potential application as carriers for controlled release of drugs, since these materials display a unique combination of properties, which might be favorable to the above use. A two component silicone gel system was used and various cross-linker ratio was applied, in order to produce networks with varying crosslink density. Swelling experiments in toluene were run in order to evaluate the network characteristics. The silicone elastomer was loaded with salicylic acid and propranolol hydrochloride and their delivery in distilled water was followed. The results showed that release is almost of zero order for high loading of salicylic acid, while delivery seems to be diffusion controlled up to a certain limit. The administered drug concentrations are relatively low if silicone discs are used, due to the hydrophobic nature of this material. On the other hand, when membranes are used with a thickness of 0.1-0.2 mm, then the delivery rate is much higher depending of course on the hydrophilic character of the drug.