United States Patent:  5,968,552

Appl. No.:  849324

The invention relates to a pharmaceutical formulation comprising diltiazem hydrochloride. The formulation is in the form of a mixture of beads blended so as to provide a dissolution profile that renders the formulation suitable for oral administration once daily.

OUTLINE OF THE INVENTION

The new formulation is characterized in the following way. Beads containing diltiazem hydrochloride are made by processes the same as or similar to those disclosed in U.S. Pat. No. 5,286,497.

However, instead of mixing only two types of beads, referred to as "rapid release beads" and "delayed release bead", three types of beads are made which will be referred to herein as "rapid release beads", "intermediate release beads", and "delayed release beads".

By using an appropriate mixture of these three types of beads, with three different amounts of coating, it is possible to obtain the desired dissolution profile for the final mix, without the need for the individual types of beads to have the sharp step-like release profile required by the invention of U.S. Pat. No. 5,286,497.

Claim 1 of 5 Claims

1. A diltiazem hydrochloride formulation suitable for once daily oral administration comprising a blend of beads, such that the following dissolution profiles are satisfied when measured in a type 2 dissolution apparatus according to U.S. Pharmacopoeia XXII at 37^oC. at 100 rpm in 0.1 NHCl:

i) a first portion of said beads exhibit the following profile:

a) not less than 40% released at 3 hours

ii) a second portion of said beads exhibits the following profile:

a) not more than 30% released at 6 hours

b) not less than 35% released at 12 hours

iii) a third portion of said beads exhibits the following profile:

a) not more than 20% released at 6 hours

b) not more than 35% released at 12 hours

c) not less than 50% released at 24 hours

iv) the blend exhibits the following profile:

a) from 20% to 45% released after 6 hours

b) from 25% to 50% released after 12 hours

c) from 35% to 70% released after 18 hours

d) not less than 70% released after 24 hours

e) not less than 85% released after 30 hours.

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