Are there any guidelines with regards to assuring the stability of pharmaceutical compounds and their solutions. That is to say is there a minimum period when stability does not have to be confirmed. Also, should stability confirmation always be by comparison to a freshly prepared solution or can a simple comparison of peak area suffice in some cases. I've heard some say where, if solutions are analyzed on the same day as prepared then stability does not have to be confirmed but as solutions are not aware of our time system I can't see the logic.

The following was taken from "Reviewer Guidance, Validation of Chromatographic Methods" available at:

http://www.fda.gov/cder/guidance/

Sample Solution Stability
Solution stability of the drug substance or drug product after preparation according to the test method should be evaluated according to the test method. Most laboratories utilize autosamplers with overnight runs and the sample will be in solution for hours in the laboratory environment before the test procedure is completed. This is of concern especially for drugs that can undergo degradation by hydrolysis, photolysis or adhesion to glassware.

Recommendations:
Data to support the sample solution stability under normal laboratory conditions for the duration of the test procedure, e.g., twenty-four hours, should be generated. In exceptional cases where multiple days are needed for sample preparation or solution storage, an appropriate stability time should be selected.

I feel solution stability always needs to be demonstrated and needs to be performed against a freshly prepared standard. Good Luck.