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Last Updated: December 12, 2025

Claims for Patent: 4,880,631

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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 6.96×10-18 to 6.96×10-14 cm3 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):	John L. Haslam, Gerald S. Rork
Assignee:	Merck and Co Inc
Application Number:	US07/100,665
Patent Claims:

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