The American Medical Association (AMA) concluded in 2001 that the actual shelf life of some products is longer than the labeled expiration date. The AMA stated the best evidence resides in the Shelf Life Extension Program (SLEP) undertaken by the FDA for the Department of Defense.2,7
The original purpose of the SLEP program was twofold: to determine the actual shelf life of stockpiled military medications for future use, and to save government dollars.5 Over 3000 lots, representing 122 different drug products, were assessed in the SLEP program. Based on stability data, expiration dates on 88% of the lots were extended beyond their original expiration date for an average of 66 months. Of these 2652 lots, only 18% were terminated due to failure. Examples of common drug products that were tested with no failures included amoxicillin, ciprofloxacin, diphenhydramine, and morphine sulfate injection. Drug expiration extension dates on these products ranged from 12 months to 184 months (over 15 years).8 Biologics are not included in the SLEP program.
These results suggest that many drug products may have extended shelf lives beyond their expiration date. However, it is difficult for any one consumer or health care provider to know which product could have an extended shelf life. The ability for a drug to have an extended shelf life would be dependent upon the actual drug ingredients, presence of preservatives, temperature fluctuations, light, humidity, and other storage conditions. Additionally, the drug lots tested in the SLEP program were kept in their original packaging. Once a drug is repackaged into another container, as often happens in the pharmacy, the shelf-life could decline due to environmental variations.