Composition for the controlled discharge of an active ingredient, and its preparation.

摘要

A composition for use in an aqueous environment, which comprises a formulation containing a water-soluble active ingredient, a semipermeable membrane surrounding the formulation, and particulate water-soluble pore-forming material dispersed within the membrane, whereby, in use in an aqueous environment, the pore-forming material is dissolved forming pores in the semipermeable membrane, the active ingredient is taken up in solution thus creating an osmotic pressure gradient across the membrane between the solution and the aqueous environment, and water from the aqueous environment is diffused through the semipermeable membrane into contact with the active ingredient concurrently while a solution of the active ingredient is discharged through the pores of the membrane into the aqueous environment. The composition has application in the fields of human and veterinary medicine and also in the field of agriculture.