Medication Expiration Dates
How are expiration dates assigned to compounded medications?
The board of pharmacy of the state of residence of a compounding pharmacy is the regulating body that sets forth guidelines for the assignment of expiration dates (i.e., shelf lives) by compounders in that state. Most states have adopted the expiration date labeling rubric promulgated by the U.S. Pharmacopeial Convention (USP), and there are many gradations on the labeling spectrum. Shelf lives range from 24 hours for some water-based sterile injectables to 360 days for some nonaqueous, solid preparations.
Several considerations must be made before giving a compound an expiration date. For example but not inclusive of all factors: Is it a sterile or nonsterile compound? Does it contain water? What is the expiration date of the ingredient with the shortest shelf life?
Many states also allow compounding pharmacies to send samples of their compounds to independent analytical laboratories to assess potency and stability at a preselected time point. For example, Monument Pharmacy submitted a sample of its methimazole transdermal gel to a lab for analysis of stability and potency at 90 days. The sample’s integrity was satisfactorily noted at the 90-day mark according to the lab report we received. The Colorado Board of Pharmacy allowed us to assign a 90-day expiration date to that compound, which was much longer than the board’s labeling guidelines would typically allow.
If a compounding pharmacy makes an ingredient or formulation change to a previously tested compound, the compounder must either submit a new sample for independent laboratory analysis or use the state board of pharmacy’s expiration date assignment rubric.