Drug product intrinsic stability

Other factors, such as lack of experience at the new site in a particular dosage form or difference in the environmental conditions between the sites, can potentially affect the quality or stability of a drug product. Therefore, one site-specific batch may not be sufficient in these cases. More than one site-specific batch may be needed for a drug substance or product that is intrinsically unstable. 

Polymorphism may well be a significant problem with freeze-dried products. However, the issue of practical significance lies normally along the amorphous vs. crystalline pathway, rather than being concerned about which particular crystalline polymorph forms. In general, a crystalline drug implies better stability, but if crystallization of an excipient occurs, the result is normally inferior stability. Of course, if the drug is intrinsically stable in any form, then crystallization will have no stability implication. Finally, it should be emphasized poor inter- or intra-batch uniformity can result in systems where crystalliza-... 

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