Impact of the reclassification of omeprazole on the prescribing and sales of ulcer healing drugs.

OBJECTIVES: To investigate if the reclassification of omeprazole from a prescription only medicine to pharmacy sale status had an impact on the prescribing and sales of ulcer-healing drugs and whether deprivation had any influence on this. SETTING: Primary care, Wales, UK. METHOD: Retrospective analysis (March 2002 to February 2005) of prescription data and pharmacy sales data. MAIN OUTCOME MEASURE: Number of items per 1,000 population. RESULTS: The number of prescription items for ulcer-healing drugs across Wales increased in each year of the study. The number of items per 1,000 population for proton pump inhibitors increased by 12.4% (473.3 to 531.8 items) in 2003/04 and 13.8% (531.8 to 605.1 items) in 2004/05, whereas the number of items per 1,000 population for H2 antagonists fell by 6.2% (149.1 to 139.9 items), and 5.7% (139.9 to 131.9 items) during 2003/04 and 2004/05, respectively. The sale of items per 1,000 population of H(2) antagonists increased by 34.3% (19.8 to 26.6 items) in 2003/04, but fell by 8.6% (26.6 to 24.3 items) in 2004/05. In February 2005, 12 months after reclassification, omeprazole accounted for 7.6% (2.0 items per 1,000 population) of the total sales (26.3 items per 1,000 population) of ulcer-healing drugs from pharmacies in Wales. Areas with high multiple deprivation and unemployment were significantly associated with the prescribing of ulcer-healing drugs, H2 antagonists and proton pump inhibitors. Multiple deprivation, unemployment and low income explained 21% of the variation in prescribing of ulcer-healing drugs. The sale of omeprazole through pharmacies was not related to these deprivation characteristics. CONCLUSION: Twelve months after the reclassification of omeprazole the market growth of H2 antagonists sold from pharmacies was halted although there was no apparent impact on the prescription of ulcer-healing drugs. As a consequence there was no saving to the health service drug budget associated with the reclassification of omeprazole.

A metabolic route of omeprazole involving conjugation with glutathione identified in the rat.

A metabolic route of omeprazole involving glutathione has been established through identification of endproducts excreted in the urine of rats after oral administration of 400 mumol/kg of a mixture of [3H]- and [14C]omeprazole. The labeled positions enabled facile tracing of metabolites that were formed through fission of omeprazole, producing [3H]pyridine and [14C]benzimidazole metabolites. The structures of the metabolites were established by HPLC thermospray MS and MS/MS. Two of the metabolites were isolated and characterized by 1H NMR studies. The fact that the N-acetylcysteine derivative of the benzimidazole was one of the endproducts indicated that the initial reaction involved glutathione. Three metabolites reflecting the fate of the pyridine moiety were identified. Their proposed formation route is via initial reduction to the pyridylmethylthiol compound followed by S-methylation and S-oxidation to the corresponding sulfoxide or sulfone. The quantity of metabolites formed via the glutathione route identified in urine was about 10% of the dose given, both in male and female rats. The male and female rats excreted the same cleaved metabolites and approximately equal quantities thereof.