Sustained release pharmaceutical capsules

Claim 1

A sustained release pharmaceutical capsule containing benzodiazepine selected from the group consisting of chloriazepoxide and diazepam in a formulation hydrodynamically balanced so that, upon contact with gastric fluid, said formulation acquires and maintains a bulk density of less than 1 thereby being buoyant in said fluid and remaining buoyant in the gastric fluid of the stomach until substantially all of said benzodiazepine contained therein has been released, said formulation comprising a finely particulate, homogeneous mixture of said benzodiazepine; from about 5% by weight to about 60% by weight of therapeutically inert, pharmaceutically acceptable adjunct materials, from 0% by weight to about 60% by weight of a fatty material having a specific gravity of less than one and from about 20% by weight to about 75% by weight of one or a mixture of hydrocolloids selected from the group consisting of methyl cellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, hydroxymethylcellulose and sodium-carboxymethylcellulose to provide, upon contact with gastric fluid, a water-impermeable barrier on the surface of said formulation.