Stability drug substance

H. Container and Closure System L Drug Substance Stability... 

Confirm formulation composition, including, but not limited to, drug substance content, drug substance stability, excipient levels, water, and residual solvents, using appropriately characterized methods. 

Evaluate drug substance stability, including protocol preparation, approval, and study conduct. 

Seen in drug substance stability samples at >0.05%, but not in purposeful degradation... 

With these limitations in mind, this chapter concentrates on the specific considerations which are fundamental to the development of pharmaceutical dosage forms designed for application to the skin. Many of the early pharmaceutical development stages for these dosage forms, such as preformulation and drug substance stability, are common to dosage forms designed for other routes of delivery. These have been fully discussed elsewhere in this volume and will not be discussed in depth here. 

Tests demonstrating drug substance stability take several forms, some of which were mentioned above. 

Drug substance stability is also addressed in analytical methods development validation studies that require a demonstration of selectivity as part of specificity testing. These results are included in CMC submissions in support of the analytical methods. In this testing, drug substance is commonly stressed with acid, base, oxidation, air, heat, light and other conditions to give rise to products that can be separated from the parent compound. 

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