Risk of negative results associated with proton pump inhibitors: review of electronic prescription in polymedicated patients

Introduction: Extensive use of proton pump inhibitors (PPI) can result in an increased risk of drug interactions. Aged polypharmacy patients are a source of particular concern. A systematic electronic prescription (EP) review allows detection of potential drug – drug interactions.

Material and methods: Retrospective, transversal, observational study: review of e-prescription orders received during 2015 in our community pharmacy.

Results: 1186 EP dispensed to 164 patients (age 65.7±17.2), 52 patients in 71-80 range. 11.0±5.6 medicines per patient. 27% IBP EP with no approved indication. 77% EP used as gastroprotective agent. As far as omeprazole is concerned, risk of negative outcomes associated with medication (NOM) detected in 29 patients (30%), 15 of them taking the drug without approved indication. Most prevalent comorbidities: hypertension (n=81), dyslipidemia (n=61) and diabetes (n=36). Drugs responsible for potential interaction: acenocoumarol, iron, cyanocobalamin, escitalopram, benzodiazepines and clopidogrel.

Discussion: 80% of omeprazole EP were dispensed to patients aged 61–90. Coupled with multimorbidity and polypharmacy, the duration of the treatment exceeded directions for use in most of the cases. Chronification and increase of NOM may be due to lack of an appropriate patient follow-up procedure.

Many of the drugs responsible for omeprazole interactions were prescribed to treat most prevalent health problems. Thus, risk of NOM does not appear to depend on PPI appropriate indication.

Conclusions: EP review let us to assess the risk of suffering from a NOM. Reviewing pharmacokinetic PPI interaction profile allows to depict the basics for a later intervention.

During EP review, safety and necessity NOMs were recorded in similar percentages. Most relevant interactions found for omeprazole occur during metabolism of the drugs.