Semisolid drugs changes

Pharmacists should also take a dim view of changes in the particle size, size distribution, or particulate nature of semisolid suspensions. They are the consequence of crystal growth, changes in crystalline habit, or the reversion of the crystalline materials to a more stable polymorphic form. Any crystalline alteration can lead to a pronounced reduction in the drug-delivery capabilities and therapeutic utility of a formulation. Thus, products exhibiting such changes are seriously physically unstable and unusable. 

The key parameter for any drug product is its efficacy as demonstrated in controlled clinical trials. The time and expense associated with such trials make them unsuitable as routine quality control methods. Therefore, in vitro surrogate tests are often used to assure that product quality and performance are maintained over time and in the presence of change. A variety of physical and chemical tests commonly performed on semisolid products and their components (e.g., solubility, particle size and crystalline form of the active component, viscosity, and homogeneity of the product) have historically provided reasonable evidence of consistent performance. More recently, in vitro release testing has shown promise as a means to comprehensively assure consistent delivery of the active component(s) from semisolid products. 

Guidance for industry, Nonsterile semisolid dosage forms Scale-up and postapproval changes, U.S. Food and Drug Administration, May 1997, pp. 1-37. 

Guidance for Industry Nonsterile Semisolid Dosage Forms Scale-Up and Postapproval Changes Chemistry, Manufacturing, and Controls In Vitro Release Testing and In Vivo Bioequivalence Documentation. U.S. Department of Health and Human Services Food and Drug Administration Center for Drug Evaluation and Research (CDER), May 1997. 

Non-Sterile Semisolid Dosage Forms Scale-Up and Post Approval Changes Center for Drug Evaluation and Research (CDER) May 1997 FDA Guidance for Industry. 

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