Abstract
Acid-suppressing drugs and anticoagulants are used increasingly in general practice. Warfarin is potentiated by some acid-suppressing drugs, notably cimetidine and omeprazole, through interference of the cytochrome P450 system. This study aimed to ascertain the extent of co-prescribing of warfarin and acid-suppressing drugs in general practice. We conducted a retrospective survey of the records of all patients prescribed acid-suppressing drugs over a 2-year period to ascertain those who had also taken warfarin; we also made a cross-sectional survey of all patients on warfarin to ascertain those who had taken acid-suppressing drugs. From a general practice population of 45 574 patients in northern England, 3423 (7.5%) had been prescribed acid-suppressing drugs during the previous 24 months. Of 274 patients who had been on warfarin, 44 (16.1%) had also taken acid-suppressing drugs (26 H2 receptor blockers and 18 proton-pump inhibitors). The commonest reasons for anticoagulation were thrombo-embolic disease (40.9%), atrial fibrillation (36.4%), valvular heart disease (18.2%), and surgical prophylaxis (4.5%). The indications for concurrent acid-suppressing drugs were: `dyspepsia' 38.6%, reflux 22.7%, oesophagitis 13.6%, duodenal ulcer 13.6%, gastric ulcer 4.5%, unknown 6.8%. There have been no studies from primary care to evaluate the possible clinical effects of the concomitant use of acid-suppressing drugs and warfarin; some fluctuations in coagulation control, particularly in patients taking the combinations intermittently, may be due to this. Keywords: H2 receptor blockers; acid-suppressing drugs; warfarin; proton pump inhibitors
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Selected References
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- Arnold R. Safety of proton pump inhibitors--an overview. Aliment Pharmacol Ther. 1994;8 (Suppl 1):65–70. doi: 10.1111/j.1365-2036.1994.tb00265.x. [DOI] [PubMed] [Google Scholar]
- Rubin G. P., Contractor B., Bramble M. G. The use of long-term acid-suppression therapy. Br J Clin Pract. 1995 May-Jun;49(3):119–120. [PubMed] [Google Scholar]
- Sutfin T., Balmer K., Boström H., Eriksson S., Höglund P., Paulsen O. Stereoselective interaction of omeprazole with warfarin in healthy men. Ther Drug Monit. 1989;11(2):176–184. doi: 10.1097/00007691-198903000-00010. [DOI] [PubMed] [Google Scholar]
- Unge P., Svedberg L. E., Nordgren A., Blom H., Andersson T., Lagerström P. O., Idström J. P. A study of the interaction of omeprazole and warfarin in anticoagulated patients. Br J Clin Pharmacol. 1992 Dec;34(6):509–512. doi: 10.1111/j.1365-2125.1992.tb05656.x. [DOI] [PMC free article] [PubMed] [Google Scholar]