Q: Can you suggest a formulation or approach for the preparation of an oral suspension of omeprazole?
A: For the past few years, pharmacists have used the Reflux Solutions products ChocoBase and CaraCream to compound suspensions of proton pump inhibitors such as omeprazole. These products were discontinued in December 2004. Omeprazole (Zegerid from Santarus) 20-mg powder for oral suspension was released in October 2004. The company states that the formulation is based on patents licensed from the University of Missouri expiring in July 2016. Santarus also announced that it would release a 40-mg packet in the first quarter of 2005. Pharmacists should use commercially prepared New Drug Application (NDA) or Abbreviated New Drug Application (ANDA) products when they are available for patient therapy. In some cases, however, patient-specific, documented medical/therapeutic occurrences may require extemporaneous compounding, such as patient intolerance to a particular ingredient in the NDA or ANDA ("commercial") product.
Prior to the availability of ChocoBase and CaraCream, published studies indicated long-term shelf stability of omeprazole in 8.4% sodium bicarbonate solution. Subsequent clinical studies indicated that sodium bicarbonate 8.4% might not provide adequate buffer capacity to overcome stomach acidity, resulting in variable bioavailability due to the instability of omeprazole in acid. The information supported the use of ChocoBase and CaraCream, for which studies seemed to indicate greater "protection" of the omeprazole, presumably from oils in the formulations. Other studies indicate that an increase in the alkalinity of the formulation can provide adequate buffer for therapeutic effectiveness of an extemporaneously compounded formulation of omeprazole suspension, but alkaline solutions create compliance difficulties because of taste.
Because the studies of the bioavailability of omeprazole extemporaneously compounded in oral suspension conflict, it seems reasonable to employ this formulation when necessary:Omeprazole 20-mg capsules 5
Combine powder with sodium bicarbonate solution. Store in refrigerator at 5ºC: stable 30 days (Quercia FA, Fan C, et al. Stability of 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.