Claims for Patent: 5,150,718

Summary for Patent: 5,150,718

Title:	Method of contraception
Abstract:	The invention relates to an implant of polymeric material which can release a contraceptive agent for a relatively long time when fitted subcutaneously or locally.
Inventor(s):	De Nijs; Hendrik (Oss, NL)
Assignee:	Akzo N.V. (Arnhem, NL)
Application Number:	07/836,632
Patent Claims:	1. A method of contraception comprising: subcutaneously or locally administering an implant said implant comprising: core material of ethylene/vinyl acetate copolymer having such a molecular weight that the melt index is equal to or greater than 10 grams/10 minutes, and a vinyl acetate content of at least 20% by weight, which core material functions as a matrix for at least one highly active progestogen present in a quantity sufficient for a release rate of greater than 30 .mu.g of said progestogen per day over a term of at least one year, and a membrane having a layer thickness of 50-250 .mu.m which encases the core material and also consists of ethylene/vinyl acetate copolymer, but with such a molecular weight that the melt index is less than or equal to 10 grams/10 minutes, and a vinyl acetate content of less than 20% by weight, which membrane, with the core material, forms a contact layer at the interface of the core material and membrane thus preventing the core material and membrane, from separating from one another. 2. The method of claim 1, wherein the core material of said implant comprises an ethylene/vinyl acetate copolymer with a melt index between 25 and 30 grams/10 minutes and a vinyl acetate content of greater than 25% by weight. 3. The method of claim 1, wherein the membrane of said implant comprises an ethylene/vinyl acetate copolymer with a melt index less than or equal to 8 grams/10 minutes and a vinyl acetate content of less than 20% by weight. 4. The method of claim 1, wherein the highly active progestogen comprises 3-ketodesogestrel. 5. The method according to claim 1, wherein said implant is of essentially cylindrical shape with a maximum external diameter of about 2 mm and a length of less than about 5 cm. 6. The method of claim 1, wherein said core of the implant comprises about 50 to 75% contraceptive substance and from about 50 to 25% ethylene vinyl acetate copolymer. 7. The method of claim 6, wherein the ends of the implant are covered by an inert polymer. 8. The method of claim 3, wherein the implant further comprises a layer of polysiloxane coating the entire implant.