Claims for Patent: 4,880,631

Summary for Patent: 4,880,631

Title:	Controlled porosity osmotic pump
Abstract:	The instant invention is directed to an osmotic pump, for the controlled release of diltiazem L-malate to an environment of use, said pump comprising: (A) a core which comprises a therapeutically effective amount of diltiazem L-malate and an effective buffering amount of sodium bitartrate surrounded by (B) a rate controlling water insoluble wall, having a fluid permeability of 6.96.times.10.sup.-18 to 6.96.times.10.sup.-14 cm.sup.3 sec/g and a reflection coefficient of less than 0.5, prepared from: (i) a polymer permeable to water but impermeable to solute and (ii) 0.1 to 60% by weight, based on the total weight of (i) and (ii), of at least one pH insensitive pore forming additive dispersed throughout said wall.
Inventor(s):	Haslam; John L. (Lawrence, KS), Rork; Gerald S. (Lawrence, KS)
Assignee:	Merck & Co., Inc. (Rahway, NJ)
Application Number:	07/100,665
Patent Claims:	1. An osmotic pump, for the controlled release of diltiazem L-malate to an environment of use, said pump comprising: (A) a core which comprises a therapeutically effective amount of diltiazem L-malate and between 80 and 150 percent by weight of sodium bitartrate surrounded by (B) a rate controlling water insoluble wall, having a fluid permeability of 6.96.times.10.sup.-18 to 6.96.times.10.sup.-14 cm.sup.3 sec/g and a reflection coefficient of less than 0.5, prepared from: (i) a polymer permeable to water but impermeable to solute and (ii) 0.1 to 60% by weight, based on the total weight of (i) and (ii), of at least one pH insensitive pore forming additive dispersed throughout said wall. 2. An osmotic pump according to claim 1 wherein the diltiazem L-malate in the core is between 30 and 500 mg. 3. An osmotic pump according to claim 1 wherein the sodium bitartrate in the core is between 30 and 500 mg. 4. An osmotic pump according to claim 1, wherein said pore forming additive comprises: (a) 0.1 to 50%, by weight, solid additive, based on the total weight of (i) and (ii), and/or (b) 0.1 to 40%, by weight, liquid additive, based on the total weight of (i) and (ii), not to exceed a total weight % of pore forming additive of 60%. 5. An osmotic pump according to claim 4 wherein said wall is 20 to 500 microns thick and said wall pores are between 10 angstroms and 25 microns in diameter. 6. An osmotic pump according to claim 1, wherein said reflection coefficient is less than 0.1. 7. An osmotic pump according to claim 1, further comprising: (C) 0 to 50 parts per 100 parts of (i) and (ii) of plasticizer and flux regulating additives and (D) 0 to 40 parts per 100 parts of (i) and (ii), of surfactant additive. 8. An osmotic pump according to claim 1, wherein said water insoluble wall is 1 to 1,000 microns thick and wherein 5 to 95% of the resulting wall pores are between 10 angstroms and 100 microns in diameter. 9. An osmotic pump according to claim 1, wherein said polymer is selected from the group consisting of cellulose esters, acylated polysaccharides, polyurethane, polymers of acrylic and methacrylic acid and esters thereof, poly (ortho ester)s, polyacetals and mixtures thereof. 10. An osmotic pump according to claim 9, wherein said polymer is selected from the group consisting of cellulose esters and acylated polysaccharides. 11. An osmotic pump according to claim 9, wherein said polymer is selected from the group consisting of polyurethanes and polymers of acrylic and methacrylic acid and esters thereof. 12. An osmotic pump according to claim 9, wherein said polymer is selected from the group consisting of poly(ortho ester)s and polyacetals. 13. An osmotic pump according to claim 1, wherein said pore forming additive is selected from the group consisting of water, alkali metal salts, alkaline earth metal salts, saccharides, aliphatic polyols, aromatic polyols and mixtures thereof. 14. An osmotic pump according to claim 1, wherein 0.1 to 50%, by weight, of said pore forming additive is used. 15. An osmotic pump according to claim 1, wherein said pH insensitive pore forming additive is selected from the group consisting of polyethylene glycol, sorbitol, glucose and mixtures thereof. 16. An osmotic pump according to claim 1, further comprising: an external layer of a pharmaceutically acceptable carrier and a therapeutically effective amount of a cardiovascular agent. 17. An osmotic pump according to claim 16 wherein the cardiovascular agent is selected from alpha receptor blocking agents, alpha and beta receptor blocking agents, angiotensin converting enzyme inhibitors, antianginal agents, antiarrhythmics, antiembolus agents, antihypertensives, beta blocking agents, digitalis, hemorheologic agents, inotropic agents, myocardial infarction prophylaxis, quinidine, cerebral vasodilators, coronary vasodilators, peripheral vasodilators, and vasopressors. 18. An osmotic pump according to claim 17 wherein the cardiovascular agent is selected from angiotensin converting enzyme inhibitors. 19. An osmotic pump according to claim 18 wherein the angiotensin converting enzyme inhibitor is selected from captopril, enalapril and lisinopril. 20. An admixture of dilitiazem L-malate with between 80 and 150 percent by weight of sodium bitartrate in a drug delivery device for the controlled release of diltiazem L-malate to an environment of use.