Enhanced Release of Drugs from Silicone Elastomers (I) Release Kinetics of Pineal and Steroidal Hormones

Abstract

The release of melatonin, estradiol, and flourogestone acetate from subdermal implants was enhanced when implants were fabricated from silicone elastomers containing co-solvents. This enhancement followed a Q vs. t relationship. As glycerol concentration increased, the increments in release rate were greater for hydrophilic drugs than for hydrophobic drugs. When drug loading in the implants was held constant, release rates were found to be a function of glycerol concentrations in the device. A synergistic enhancement of release rate was observed when both glycerol and sodium chloride were added to the silicone matrix. The fact that co-solvents enhance the rate of drug release from silicone elastomers indicates that a reduction in the activation energy required for drug release may occur.