Claims for Patent: 5,728,396

Summary for Patent: 5,728,396

Title:	Sustained delivery of leuprolide using an implantable system
Abstract:	The invention is directed to a device for delivering an active agent formulation for a predetermined administration period. An impermeable reservoir is divided into a water-swellable agent chamber and an active agent formulation chamber. Fluid from the environment is imbibed through a semipermeable plug into the water-swellable agent chamber and the active agent formulation is released through a back-diffusion regulating outlet. Delivery periods of up to 2 years are achieved.
Inventor(s):	Peery; John R. (Stanford, CA), Dionne; Keith E. (Menlo Park, CA), Eckenhoff; James B. (Los Altos, CA), Landrau; Felix A. (Punta Gorda, FL), Lautenbach; Scott D. (San Mateo, CA), Magruder; Judy A. (Mountain View, CA), Wright; Jeremy C. (Los Altos, CA)
Assignee:	Alza Corporation (Palo Alto, CA)
Application Number:	08/791,699
Patent Claims:	1. An implantable leuprolide delivery system comprising: (a) an impermeable reservoir; (b) a piston that divides the reservoir into a first and a second chamber, the first and second chambers each having an open end; (c) a water-swellable agent formulation in the first chamber; (d) a leuprolide formulation in the second chamber; (e) a semipermeable plug in the open end of the first chamber; and (f) a back-diffusion regulating outlet in the open end of the second chamber; wherein the system effectively seals the second chamber and isolates the leuprolide formulation from the environment of use. 2. The system of claim 1 wherein the reservoir is titanium or a titanium alloy. 3. The system of claim 1 wherein the piston is formed of styrene-ethylene-butylene-styrene copolymer. 4. The system of claim 1 wherein the water-swellable agent formulation contains at least about 64 mg NaCl. 5. The system of claim 1 wherein the water-swellable agent formulation contains NaCl, a gelling osmopolymer and granulation and processing aids. 6. The system of claim 1 further comprising an additive in the first chamber. 7. The system of claim 6 wherein the additive is PEG 400. 8. The system of claim 1 wherein the leuprolide formulation is leuprolide acetate dissolved in DMSO at an assayed content of 37% leuprolide. 9. The system of claim 1 which contains 65 mg leuprolide. 10. The system of claim 1 wherein the semipermeable plug is formed of polyurethane material with 20% water uptake. 11. The system of claim 1 wherein the back-diffusion regulating outlet is made of polyethylene and has a flow path helical in shape with a diameter between 0.003 and 0.020 inches and a length of 2 to 7 cm. 12. The system of claim 1 which delivers about 0.35 .mu.L leuprolide formulation per day. 13. The system of claim 12 which provides continuous delivery of leuprolide formulation for about one year. 14. The system of claim 1 which reaches at least about 70% steady-state delivery by day 14. 15. The system of claim 1 which delivers about 150 .mu.g leuprolide per day. 16. A method of treating a subject suffering from prostatic cancer comprising administering at least one system of claim 1. 17. An implantable leuprolide delivery system comprising: (a) a titanium alloy reservoir; (b) a styrene-ethylene-butylene-styrene copolymer piston that divides the reservoirs into a first and a second chamber, the first and second chambers each having an open end; (c) a compressed NaCl-based osmotic engine and a PEG additive in the first chamber; (d) 65 mg leuprolide as a leuprolide acetate solution in DMSO in the second chamber; (e) a semipermeable polyurethane plug with 20% water uptake in the open end of the first chamber; and (f) a polyethylene back diffusion regulating outlet with a helical flow path in the open end of the second chamber; wherein the system continuously delivers about 150 .mu.g leuprolide per day for about one year after subcutaneous implantation.