摘要：

1. A controlled release dosage form for internal administration, comprising a solid bead and contacting and surrounding the bead a rupturable plastic, non-toxic, insoluble, non-digestible film coating which is inert to gastrointestinal fluid and permeable to diffusion of water, the bead consisting essentially of a uniform dispersion of medicament in a water-swellable colloid, the thickness of the coating and the swellability of the bead being such that on prolonged exposure to gastrointestinal fluid diffusion of water takes place through the coating into the bead causing the bead to swell and build up pressure exceeding the cohesive strength of the coating thereby resulting in outward rupture of the coating and substantially immediate and total release of the medicament from the head into the gastrointestinal fluid.

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