Drying induced polymorphic transformation of pharmaceutical ingredients: a critical review of recent progresses and challenges

Active Pharmaceutical Ingredients (APIs) are often present in more than one polymorphic form. Most of the time one of these polymorphs has better properties than others and is the desired form. However, the undesired polymorph may be generated during the production of the solid dosage form from the API. One of the unit operations that may produce undesired polymorph is drying. Drying and solvent addition are frequently used for solid dosage manufacturing since they are required for granulation, a frequently used unit operation for many pharmaceutical production lines. In this article, we present a critical review of current open literature on this subject. The goal of this review is to produce a thorough account of past and current research and indicate the future directions which will benefit the industry.