Effect of Moisture on the Stability of Solid Dosage Forms

Abstract

It has long been known that moisture affects the stability of some drug substances. Aspirin is a classical example. Aspirin is not wet granulated. Even though the water is driven off in a wet granulation, there is still sufficient moisture stress in the process to induce excessive decomposition on subsequent storage. Dry methods (slugging, roller compaction) are therefore resorted to. In other instances, the moisture sensitivity of a drug may warrant using a hard shall capsule approach. This presumes that the drug substance is not particularly hygroscopic, since, otherwise, the capsule shell will provide an unwanted source of moisture.