Expert: Michael Anisfeld - 6/24/2009

Question
Hi Michael. My question is regarding expiry dating which is usually expressed as month and year. If a pharma dosage form has a shelf life of, say, two years what is the expiry date in relation to the date of manufacture? I understand common practice is to add on two years, ie. DOM May 09 means expiry of May 2011. I have also heard, though,that some companies would use an expiry in that instance of APRIL 2011. This is because the DOM could be 1st May and having an expiry of end of May 2011 would mean a shelf life of 37 months, not 36.
Are you aware of any trend toward taking the cautious approach or of any regulatory guidelines one way or the other? Best regards, Kev.

Answer
Kevin:

The date of manufacture is the date that the ingredients first get to meet each other, say January 2, 2009. if you have a 36 month expiration date (scientifically supported by ICH-parameter stability studies), then the expiration date is pragmatically January 1, 2012. but to be safe, as you safe many companies error in caution and state an expiration of "December 2011", implying December 31, 2011.

I hope this helps.