Importance

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Abstract

A pharmaceutical oral controlled release multiple-units formulation is prepared by mixing units containing an active substance and coated with a substantially water-insoluble, but water diffusable controlled release coating with particles of an active substance, the mean size of which is at least one power of 10 smaller than the coated units under conditions which will result in adherence of the smaller particles to the surface of the controlled release coating in a substantially uniform layer. The coated units have a mean size of between about 0.1 and 1.5 mm, in particular about 0.4 to 1.2 mm, and the fine particles have a mean particle size of from about 1 to about 50 .mu.m and are present in the composition in an amount of at the most 25 percent by weight, in particular at the most 5 percent by weight and preferably not more than 1 percent by weight, calculated on the weight of the coated units. The mixing is performed in the presence of an anti-adhesive which counteracts undesired electrostatic charging such as talc or colloidal silicon dioxide. The active substance which is subject to controlled release may be potassium chloride, and the active substance of the small particles may be a diuretic. The controlled release coating contains a film-forming polymer such as ethyl cellulose, a plasticizer and a hydrophobic substance. In this manner, it is possible to combine an active substance which it is preferred to administer in a controlled release multiple-units composition, for example because it has an irritating effect on the gastric mucosa or because it has a short half life, with an instantly releasing active substance to obtain a combination composition which simplifies the dosing regimen and thus improves patient compliance.

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First Claim