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Department of Pharmaceutical Services

Prilosec (omeprazole)

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Dear Physician,

Currently there are five branded proton pump inhibitors (PPI) products available for oral administration: esomeprazole (Nexium), lansoprazole (Prevacid), omeprazole (Prilosec), Zegrid (omeprazole powder for oral suspension), pantoprazole (Protonix) and rabeprazole (Aciphex).

Omeprazole is generic and over the counter (OTC). This product has often been compared to esomerprazole (Nexium) which is the optical isomer. Claims of increased ifficacy are based upon comparisons of non-equivalent doses and any advantaes seem sall and clinically unimportant for these drugs. When esomeprazole 20 mg was compared to 20 mg of omeprazole for reflux disease no significant differences were noted. Nexium, Protonix, and Prevacid cost an average of $4 per capusle while generic omeprazole 20 mg is $0.55 or 55 cents.

Most new drugs are marketed as single enantiomers but many older drugs are still available in racemic form. As drugs reach the end of patent life, manufacturers market single enamtiomer equivalents.  Such examples include escitalopram versus citalopram (Celexa/Lexapro), esomeprazole vs. omeprazole (Nexium/Prilosec) and levalbuterol vs. albuterol. Claims of increased efficacy are based upon comparisons of non-equivalent doses and any advantages seem small and clinically unimportant for these drugs.

For example, comparing 40mg of esomeprazole would be more or less the same as comparing double the dose of omeprazole.  When esomeprazole 20mg was compared to omeprazole 20mg for reflux disease no significant differences were noted. There is no evidence of fewer adverse reactions compared with equipotent doses of omeprazole.

Summary: All proton pump inhibitors appear to be clinically comparable, and the clinical choice should be based upon pharmaco-economic considerations. Omeprazole provides the opportunity to decrease acquisition costs and co-payments for your patients.

References:
1. R.M.Klok, M.J. Postma, B.A. Van Hout, J.R.B.J. Brouwers. Meta-analysis: comparing the efficacy of proton pump inhibitors in short-term use.  Aliment Pharmacol Ther 2003; 17:1237-1245
2. P. Mansfield, D. Henry, A Tomkin. Single-enamtiomer drugs Clin Pharmacokinet 2004; 43(5):287-290

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