We have a dispute in the pharmacy about beyond-usedating (BUD) of topical preparations where no stabilityinformation is available. One of us thinks that thecreams and ointments are solids and therefore must beassigned BUD of 6 months when a United States Pharmacopeia(USP) or National Formulary bulk powder is the source of theactive ingredient. Another of us wants to assign 14 days, basedon the presence of water. Can you help clarify?
USP 29<795>, Pharmaceutical Compounding—Nonsterile Preparations, provides guidance for assigningBUD where no stability information specific to theformulation is available. When reading this material and contemplatingthe assignment of such dating, it is important forus as pharmacists to use professional judgment. It also is helpfulto refer to reliable sources for background informationwhen considering apparent conflicts within a particular scientificreport, official guidance, or official compendium.
Reportedly, 3 factors to consider when evaluating the lengthof time a drug dose form might be considered "available" tothe patient are temperature, moisture, and pH. Generally,excessive moisture shortens the "life" of a dose form by causingphysical effects such as capsule gelatin degradation and"clumping" of ingredients, and also chemical degradationwhen the drug is in solution (suspensions might reasonably beincluded). In both cases, the term excessive is relative to thesituation.
Additionally, a helpful "decision tree" was published in theInternational Journal of Pharmaceutical Compounding(Standard operating procedure: assignment of a beyond-usedate for compounded preparations. IJPC. 4:474-475).
The "tree"provides a "process of elimination" for assigninga BUD, beginning with a decision as to whether a preparationis a "solid." In the case you mention (creams—pharmaceuticallydefined as ointments) are at best semi-solid. The treethen leads to a decision as to whether the preparation is a liquid—which it clearly is not. Therefore, ointments and creamsfall into the "All other dosage forms" category and might reasonablybe assigned BUD "not later than the intended durationof therapy or 30 days, whichever is earlier." [USP 29 <795>]
Mr. Erickson is director of professional affairs at Gallipot Inc.
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