Preparation and in-vitro evaluation of a biodegradable carrier system for inducing spawning in fish

Repeated injections of hormone drugs to fish reared in captivity during the spawning season is a routine procedure for local fishermen in Taiwan. To prevent stress resulting from multiple administrations, we developed a delivery system using poly(D,L-lactide-co-glycolide) (PLGA) as a carrier. Two drugs, human chorionic gonadotropin (HCG) and leutenizing hormone-releasing hormone Analog-2 (LHRH-A₂), which are commonly used by fishermen, were loaded into polymeric microbeads. The microbeads released more than 20% of the loaded drug in an initial burst. However, drug readsorbed to the carrier and 100% release was not achieved in the in vitro studies. For induction of spawning, burst release accompanied by subsequent slow release is a potential single injection administration system.