Q: Can you suggest a formulation or approach for the preparationof an oral suspension of omeprazole?
A: For the past few years, pharmacists have used the RefluxSolutions products ChocoBase and CaraCream to compoundsuspensions of proton pump inhibitors such as omeprazole. Theseproducts were discontinued in December 2004. Omeprazole(Zegerid from Santarus) 20-mg powder for oral suspension wasreleased in October 2004. The company states that the formulationis based on patents licensed from the University of Missouri expiringin July 2016. Santarus also announced that it would release a40-mg packet in the first quarter of 2005. Pharmacists should usecommercially prepared New Drug Application (NDA) or AbbreviatedNew Drug Application (ANDA) products when they are availablefor patient therapy. In some cases, however, patient-specific, documentedmedical/therapeutic occurrences may require extemporaneouscompounding, such as patient intolerance to a particularingredient in the NDA or ANDA ("commercial") product.
Prior to the availability of ChocoBase and CaraCream, publishedstudies indicated long-term shelf stability of omeprazole in 8.4%sodium bicarbonate solution. Subsequent clinical studies indicatedthat sodium bicarbonate 8.4% might not provide adequate buffercapacity to overcome stomach acidity, resulting in variable bioavailabilitydue to the instability of omeprazole in acid. The informationsupported the use of ChocoBase and CaraCream, for which studiesseemed to indicate greater "protection" of the omeprazole, presumablyfrom oils in the formulations. Other studies indicate that anincrease in the alkalinity of the formulation can provide adequatebuffer for therapeutic effectiveness of an extemporaneously compoundedformulation of omeprazole suspension, but alkaline solutionscreate compliance difficulties because of taste.
Because the studies of the bioavailability of omeprazoleextemporaneously compounded in oral suspension conflict, itseems reasonable to employ this formulation when necessary:
Omeprazole 20-mg capsules 5
[OR Omeprazole powder 0.100 g]
Sodium bicarbonate 8.4% 50.000 mL
Combine powder with sodium bicarbonate solution. Store inrefrigerator at 5ºC: stable 30 days (Quercia FA, Fan C, et al. Stabilityof omeprazole in an extemporaneously prepared oral liquid.Am J Health Syst Pharm. 1997;54:1833-1836).
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Mr. Erickson is director of professional affairs at Gallipot Inc.