title: Long-acting injectable microsphere formulation for the parenteral administration of levonorgestrel.
abstract: The pharmacokinetic and pharmacodynamic effects of a long-acting formulation of levonorgestrel microencapsulated in a biodegradable polymer poly(DL-lactide-CO-glycolide) was tested in baboons. The polymer microspheres provided continuous release of levonorgestrel for up to 6 months following a single intramuscular injection. The treatment inhibits ovarian function for 3-6 months, depending on the dose. The duration and pattern of levonorgestrel release varies according to the quality and size of the microspheres. The microsphere delivery system offers a promising new approach to developing a long-acting injectable contraceptive based on levonorgestrel.
mesh_terms: D000818:Animals; D004339:Drug Compounding; D005260:Female; D007263:Infusions, Parenteral; D007273:Injections, Intramuscular; D007700:Kinetics; D016912:Levonorgestrel; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D009644:Norgestrel / Q000008:administration & dosage*; D010215:Papio; D011108:Polymers; D013997:Time Factors
chemical_list: D011108:Polymers; D009644:Norgestrel; D016912:Levonorgestrel