| abstract |
A diltiazem pellet formulation for oral administration comprises a core of diltiazem or a pharmaceutically acceptable salt thereof in association with an organic acid, and a multi-layer membrane surrounding the core and containing a major proportion of a pharmaceutically acceptable film-forming, water insoluble synthetic polymer and a minor proportion of a pharmaceutically acceptable film-forming, water soluble synthetic polymer. The number of layers in the membrane and the ratio of the water soluble to water insoluble polymer being effective to permit release of diltiazem from the pellet at a rate allowing controlled absorption thereof over a twelve hour period following oral administration. The pellet has a dissolution rate in vitro which when measured in a dissolution apparatus (Paddle) according to U.S. Pharmacopoeia XXI in 0.05 M KCl at pH 7.0 results in not more than 35% of the total diltiazem being released after 2 hours of measurement. Not more than 80% of the total diltiazem is released after six hours of measurement and not less than 85% of the total diltiazem is released after 13 hours of measurement. |