Claims for Patent: 4,559,222

Summary for Patent: 4,559,222

Title:	Matrix composition for transdermal therapeutic system
Abstract:	Mineral oil (MO) polyisobutylene (PIB), colloidal silicon dioxide (CSD) mixtures suitable for use as drug containing matrices in transdermal delivery systems are disclosed. Preferred systems for dispensing moderately mineral oil soluble drugs contain at least about 6% CSD, have a MO/PIB of at least 1.0 and a viscosity of at least 1.5.times.10.sup.7 poises. Preferred systems for dispensing clonidine have a clonidine permeability of at least 1.0.times.10.sup.-4 .mu.g/cm sec and a MO/PIB of at least 1.2.
Inventor(s):	Enscore; David J. (Mountain View, CA), Gale; Robert M. (Mountain View, CA)
Assignee:	ALZA Corporation (Palo Alto, CA)
Application Number:	06/491,490
Patent Claims:	1. A composition of matter suitable for use as a matrix in a drug delivery system comprising mineral oil, polyisobutylene, a moderately mineral oil soluble drug and at least 6% colloidal silicon dioxide, the MO/PIB ratio being at least 1.0, and being characterized by having a viscosity of at least 1.5.times.10.sup.7 poise. 2. The composition of claim 1 wherein said moderately mineral oil soluble drug is dispersed therethrough in amounts up to about 40%. 3. The composition of claim 2 wherein said drug is present at a level between the saturation concentration of said drug in the composition and about 20%. 4. The composition of claim 3 wherein the ratio of mineral oil to polyisobutylene is at least 1.2 and the composition contains at least 7.5% by weight colloidal silicon dioxide. 5. The composition of claim 4 wherein said drug is selected from the group consisting of clonidine, scopolamine, propranolol, estradiol, phenylpropanolamine, ouabain, salbutamol, guanabenz, labetolol, atropine, haloperidol, bromocryptine, chloropheniramine, metrifonate, isosorbide dinitrate and nitroglycerin. 6. The composition of claim 1 wherein said drug is clonidine and the permeability of the composition to clonidine is at least 1.0.times.10.sup.-4 .mu.g/cm sec. 7. The composition of claim 6 wherein the value of MO/PIB is at least 1.2. 8. In a transdermal therapeutic system, comprising a drug reservoir layer and an adhesive layer, a moderately mineral oil soluble drug dispersed in at least said reservoir layer at a concentration above the saturation concentration of said drug in said layer and a drug release rate release controlling membrane disposed between said reservoir and adhesive, said reservoir and said adhesive layer comprising a mixture of mineral oil and polyisobutylene, the improvement wherein said reservoir and said adhesive layer contain at least about 6% colloidal silicon dioxide, have a viscosity of at least 1.5.times.10.sup.7 poise and and a ratio of mineral oil to polyisobutylene in the reservoir and adhesive of at least 1.2. 9. The transdermal therapeutic system of claim 8 wherein said release rate controlling membrane contains mineral oil and the overall ratio of MO/PIB in the transdermal therapeutic system is at least 1.4 10. The transdermal therapeutic system of claim 9 wherein said drug is selected from the group consisting of clonidine, scopolamine, propranolol, estradiol, phenylpropanolamine, ouabain, salbutamol, guanabenz, labetolol, atropine, haloperidol, bromocryptine, chloropheniramine, metrifonate, isosorbide dinitrate and nitroglycerin. 11. The system of claim 9 wherein said drug is clonidine and the in vitro drug release rate from the system to an infinite sink is at least B 2.0 .mu.g/cm.sup.2 hr. 12. In a drug containing matrix composition consisting of a gel of mineral oil and polyisobutylene having a moderately mineral oil-soluble drug dispersed therethrough, the improvement wherein said composition has at least about 6.0% colloidal silicon dioxide dispersed therethrough, an MO/PIB ratio of at least 1.0 and a viscosity of at least about 1.5.times.10.sup.7 poise. 13. The matrix composition of claim 11 wherein said MO/PIB ratio is at least about 1.2, the colloidal silicon dioxide is present in amounts of between 6 and 10% and said drug is present in an amount no less than saturation concentration and no greater than about 40%. 14. The composition of claim 12 wherein said drug is clonidine and the permeability of the matrix to clonidine is at least 1.times.10.sup.-4 .mu.g/cm sec. 15. The composition of claim 1 wherein said polyisobutylene has an average molecular weight in the range of about 35,000 to about 1,500,000. 16. The composition of claim 5 wherein said polyisobutylene has an average molecular weight in the range of about 35,000 to 1,500,000. 17. The composition of claim 7 wherein said polyisobutylene has an average molecular weight in the range of about 35,000 to 1,500,000. 18. The composition of claim 13 wherein said polyisobutylene has an average molecular weight in the range of about 35,000 to 1,500,000.