Back in 2016, FDA indicated that it was planning to issue a guidance document to explain to firms how to extend expiration dating for doxycycline tablets and capsules held in national stockpiles (here) . Doxycycline is stored in national stockpiles for treatment of post-exposure prophylaxis (PEP) or treatment of inhalational anthrax in the event of an anthrax emergency. Well, today, the FDA finally issued this guidance entitled Extending Expiration Dates of Doxycycline Tablets and Capsules in Strategic Stockpiles Guidance for Government Public Health and Emergency Response Stakeholders (here). If you can say that in one breath, you have clearly not been exposed to anthrax!
The guidance provides the testing requirements for doxycycline products that are not older than 6 years past the manufacturer’s original expiration date, as well as those that are beyond the 6-year period. The guidance provides tables that outline the testing requirements. The primary difference for the two testing scenarios is the use of accelerated stability testing for those products beyond the 6-year time period, and the start date that can be used for the extension. The 2-year extension can begin at the manufacturer’s expiration date for those product less than 6 years beyond the manufacturer’s original expiration date, rather than from the date of the testing (recommended to be 6 months prior to the extension so FDA has sufficient time to review and accept the data), and from the time 0 point for accelerated stability study test for those past the 6-year time period. These testing scenarios apply to product stored at the manufacturer’s recommended storage conditions. For product not stored at those required conditions, the Table 2 requirements (accelerated stability testing) should be performed.
FDA reminds firms that the expiration extension dating protocols can ONLY be used for doxycycline stored in the emergency national stockpiles. FDA also notes that, based on the historical experience with doxycycline, the product is very stable and the use of the USP monograph testing is stability- indicating and FDA does not expect significant growth of degradants if the product is properly stored.
The guidance also notes that patients should be informed of the expiration dating extension prior to being administered the drug. This will allow the patient to decide whether to refuse the product in favor of one within original manufacturer’s expiration dating period if available at a local pharmacy. But, in reality, who would refuse treatment in an emergency?