We have a dispute in the pharmacy about beyond-use dating (BUD) of topical preparations where no stability information is available. One of us thinks that the creams and ointments are solids and therefore must be assigned BUD of 6 months when a United States Pharmacopeia (USP) or National Formulary bulk powder is the source of the active ingredient. Another of us wants to assign 14 days, based on the presence of water. Can you help clarify?
USP 29<795>, Pharmaceutical CompoundingNonsterile Preparations, provides guidance for assigning BUD where no stability information specific to the formulation is available. When reading this material and contemplating the assignment of such dating, it is important for us as pharmacists to use professional judgment. It also is helpful to refer to reliable sources for background information when considering apparent conflicts within a particular scientific report, official guidance, or official compendium.
Reportedly, 3 factors to consider when evaluating the length of time a drug dose form might be considered "available" to the patient are temperature, moisture, and pH. Generally, excessive moisture shortens the "life" of a dose form by causing physical effects such as capsule gelatin degradation and "clumping" of ingredients, and also chemical degradation when the drug is in solution (suspensions might reasonably be included). In both cases, the term excessive is relative to the situation.
Additionally, a helpful "decision tree" was published in the International Journal of Pharmaceutical Compounding (Standard operating procedure: assignment of a beyond-use date for compounded preparations. IJPC. 4:474-475).
The "tree"provides a "process of elimination" for assigning a BUD, beginning with a decision as to whether a preparation is a "solid." In the case you mention (creamspharmaceutically defined as ointments) are at best semi-solid. The tree then leads to a decision as to whether the preparation is a liquidwhich it clearly is not. Therefore, ointments and creams fall into the "All other dosage forms" category and might reasonably be assigned BUD "not later than the intended duration of therapy or 30 days, whichever is earlier." [USP 29 <795>]
Mr. Erickson is director of professional affairs at Gallipot Inc.
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