| abstract |
The invention relates to the controlled release of calcium sulfate as well as to the controlled release of an additive to a calcium sulfate matrix, such as drugs or pesticides; controlled release is achieved by a pellet comprising calcium sulfate; The pellet is prepared by the procedure which comprises mixing the powder consisting essentially of alpha-calcium sulfate hemihydrate, a solution comprising water and, optionally, an additive and a powder consisting essentially of beta-calcium sulfate hemihydrate to form a mix and transform into a pellet, where the alpha-calcium sulfate hemihydrate and beta-calcium sulfate hemihydrate powders have special properties, such as surface areas, densities, average particle sizes and purities of BET; the dissolution rate of the calcium sulfate pellet is controlled by varying the weight ratio of the beta-calcium sulfate hemihydrate powder to the alpha-calcium sulfate hemihydrate powder from 0 to about 3; The invention also provides a method for releasing medication in vivo by implanting a pellet prepared with medication into a human or animal. |