[Pharmaceutical Characterization of Silicone Elastomer Implant System Containing Chlormadinone Acetate for Prevention of Estrus in Bitches]

We developed a new subdermal silicone elastomer implants containing chlormadinone acetate (CMA), which was effective for prevention of estrus in bitches. The implants gave a continuous CMA release over a year. The CMA release from the implants was dependent on the CMA loading level and surface area of the implants. The CMA release patterns both in vitro and in vivo system fitted well with the Higuchi square root low. The dissolution test using organic solvents was found to be useful for the brief estimation of CMA release from the implants.