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Drug interactions avoided–a useful indicator of good prescribing practice
Author(s) -
Williams D.,
Kelly A.,
Feely J.
Publication year - 2000
Publication title -
british journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.216
H-Index - 146
eISSN - 1365-2125
pISSN - 0306-5251
DOI - 10.1046/j.1365-2125.2000.00177.x
Subject(s) - medicine , warfarin , cimetidine , famotidine , drug interaction , theophylline , drug , ranitidine , pharmacology , phenytoin , medical prescription , atrial fibrillation , psychiatry , epilepsy
Aims To develop an index of quality prescribing in general practice by investigating the incidence of potential drug interactions when medicines were coprescribed within the State supported General Medical Services (GMS) in Ireland. Methods We determined an odds ratio (OR), as a measure of the relative risk of being exposed to a potential interaction, comparing the use of the H 2 ‐receptor antagonist, cimetidine, with that of the noninteracting agents ranitidine, famotidine and nizatidine in users and nonusers of warfarin, phenytoin and theophylline. Results and conclusions In 86 510 prescriptions for the H 2 –receptor antagonists potentially interacting drugs were dispensed to 8188 (9%) patients in the Eastern Health Board Region of the GMS. We found that prescribers were significantly less likely to use cimetidine (OR = 0.20,95% CI 0.17–0.21, P < 0.001) in those patients who were coprescribed warfarin, suggesting good prescribing practice within the GMS. Similarly there was preferential use of the noninteracting H 2 –receptor antagonists in patients receiving phenytoin or theophylline and the extent of this selective prescribing was in keeping with the rank order of severity of interaction with these drugs. This novel pharmacological index may be a sensitive marker of good prescribing practice.