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Background and objective: In community pharmacies potential drug interactions between prescription only medicines (POM) and over-the-counter (OTC) drugs purchased for self-medication arise mainly in two situations: (i) if an OTC drug is purchased by a passer-by customer whose prescribed drug therapy is not known; or (ii) if a POM or an OTC drug is requested by a regular customer whose prescribed drug therapy is usually recorded. With this study we aimed to assess the prevalence of potential drug interactions with selected POM and OTC drugs in passer-by and regular customers as well as their awareness of these potential drug interactions. Methods: Data were collected in 14 community pharmacies in the region of Basel, Switzerland by observation of customer contacts and interviews with passer-by customers purchasing selected OTC drugs, and telephone-interviews with regular customers treated with selected POMs identified in community pharmacies’ databases. The selected POMs and OTC drugs are drugs which could lead to clinically relevant drug interactions of varying severity but manageable through different interventions such as adjustment of dose and its timing and/or monitoring of the therapy, and avoidance of the combination by choosing an alternative treatment. Results: Of 1183 passer-by customers observed, 164 (14·4%) purchased at least one of the selected OTC drugs. One hundred and two (62·2%) of those subjects were interviewed. Forty-three (42·2%) mentioned taking prescribed drugs, and three of them were exposed to potential drug interactions of moderate severity. Out of 592 regular customers selected from the community pharmacy database, 434 (73·3%) could be interviewed. Sixty-nine (15·9%) of them were exposed to a potential drug interaction between purchased OTC drug for self-medication and their POM. Furthermore, 116 (26·7%) regular customers were exposed to potential drug interactions within their prescribed drugs and in 28 (6·5%) multiple (≥2) potential drug interactions were found. Two hundred and three (46·8%) regular customers were aware of potential drug interactions between their POM and OTC drugs. Ninety-six (47·3%) of them were informed by their prescribing physician and 52 (25·6%) by their community pharmacist. Awareness of potential drug interaction was higher in younger customers [odds ratio (OR) 0·95; 95% confidence intervals (CI) 0·93, 0·97, P < 0·0001] and higher for drug interactions classified as ‘severe’ [OR 1·79; 95% CI 1·16, 2·77, P = 0·009]. Conclusion: Efforts to increase awareness of potential drug interactions is needed. Although community pharmacies are adequately equipped with computerized drug interaction surveillance systems this is often not applied to self-medication. Vigilance for potential interactions of all drugs, including those sold over the counter, should be increased. [ABSTRACT FROM AUTHOR]

Background and objective: Drug-interaction alert systems are commonly used in community pharmacies to identify potential drug–drug interactions. However, depending on the software default setting, pharmacists may override alerts because they are too numerous. We explored the handling of drug-interaction alerts by community pharmacies in Switzerland. Methods: Data were collected by 15 trained pharmacy students in 15 Swiss community pharmacies. The medication history and the drug-interaction alerts of 600 patients who had ≥2 drugs on prescription were assessed, and the pharmacists in charge were interviewed about their management of drug-interaction alerts. Results: In the 15 pharmacies studied, the computer systems were programmed to flag only ‘severe’ drug interactions in four, ‘severe or moderate’ in six or ‘severe, moderate or minor’ in five pharmacies. The median frequency of drug-interaction alerts increased with decreasing default severity level from 0.5 to 40, respectively, to 76 per 40 patient visits and pharmacy. Because of these default settings, 277 (35·2%) of 787 potential drug-interaction alerts on new or repeated prescriptions were overridden by the computer systems. Only 256 (32·5%) of 787 potential drug interactions emerged from new prescriptions. The alert systems produced 656 alerts of which 146 were irrelevant because of multiple alerting of the same interaction or of drug combinations currently no longer taken. Of the 510 remaining relevant drug-interaction alerts, 289 (56·7%) were overridden by community pharmacists without any action taken. If the pharmacist took care of a patient's prescription him- or herself (as opposed to just controlling a prescription after a technician took care of the patient), fewer drug-interaction alerts were overridden by the pharmacist [Odds ratio (OR) 0·6, 95% confidence interval (CI) 0·42–0·98; P = 0·042). Technical overrides (by default settings) and pharmacists’ overrides together accounted for 71·9% (566 of 787 potential drug interactions). Of the remaining 211 interactions alerts, 87 (41·2%) were checked more closely by consulting the literature, contacting the prescribing physician or discussion with the patient. This led to 55 (63·2%) interventions (close monitoring, adjustment of dose or ingestion time, therapy stop or switching to alternative therapy). Determinants associated with action taken after an interaction alert were potential high severity (severe or moderate) (OR 3·34, 95% CI 1·77–6·31; P < 0·001) and alert flagged for the first time (OR 3·76, 95% CI 1·98–7·14; P < 0·001). All severe potential drug interactions ( n = 10) generated an alert and all caused an intervention. Conclusions: Pharmacists override a substantial proportion of drug-interaction alerts of minor or moderate potential severity by ignoring them or by programming the system to only flag drug interactions of potentially high severity. More sophisticated systems with improved sensitivity and specificity are required. Until these become available, it is important to ensure that at least potentially severe drug interactions are not missed; a goal that seems to be largely achieved. [ABSTRACT FROM AUTHOR]