title: Controlled drug release from polymeric delivery devices IV: in vitro--in vivo correlation of subcutaneous release of norgestomet from hydrophilic implants.
abstract: The in vitro and in vivo releases of norgestomet from hydrophilic implants were found to follow a matrix-controlled (Q - t1/2) process. The sorption of drug onto the implants was observed to obey the same mechanism but with a much smaller magnitide of the Q/t1/2 value. The effect of the extent of cross-linking on the magnitude of drug release (Q/t1/2) profiles was analyzed both theoretically and experimentally. The release of norgestomet from hydrophilic implants was found to be an energy-linked process. Two energy terms were calculated; the activation energy for matrix diffusion was 7.71 kcal/mole, and the heat of drug crystal solvation was 25-28.6 kcal/mole.
mesh_terms: D000327:Adsorption; D000818:Animals; D002417:Cattle; D002626:Chemistry, Pharmaceutical; D003692:Delayed-Action Preparations; D004343:Drug Implants; D005260:Female; D008689:Methacrylates; D009652:Norpregnenes / Q000008:administration & dosage*; D011108:Polymers; D011282:Pregnenediones / Q000008:administration & dosage*; D045167:Progesterone Congeners / Q000008:administration & dosage*; D012995:Solubility; D013696:Temperature; D013997:Time Factors
chemical_list: D003692:Delayed-Action Preparations; D004343:Drug Implants; D008689:Methacrylates; D009652:Norpregnenes; D011108:Polymers; D011282:Pregnenediones; D045167:Progesterone Congeners