Analysis of drug-drug interactions in spontaneous adverse drug reaction reports from EudraVigilance focusing on psychiatric drugs and somatic medication

Psychiatric diseases are often treated with several drugs. In addition, the risk of developing somatic comorbidities which may require drug therapy is higher in patients with than in patients without psychiatric diseases. Further on, the risk of drug-drug interactions (DDI) increases with the number of drugs taken. The aim of this study was to analyze whether already known DDI between psychiatric drugs and somatic medications still occur in everyday clinical practice. We analyzed 9,276 spontaneous adverse drug reaction (ADR) reports from Germany contained in the European ADR database EudraVigilance received between 2017 and 2021 for adults in which antidepressants, antipsychotics and mood stabilizers were reported as suspected/interacting. The ABDATA (a division of Avoxa—Mediengruppe Deutscher Apotheker GmbH) drug information system was used to identify already known potential DDI (pDDI) related to psychiatric drugs and somatic medications. An individual assessment of reports was performed to detect whether the pDDI actually occurred. 1,271 reports (49.7%) with 2,655 pDDI relating to 728 different potentially interacting drug pairs of psychiatric drugs and somatic medications were identified. Patients in reports with pDDI were older than patients in reports without pDDI (median 64 vs. 49 years) (p < 0.05). In addition, the number of pDDI and the number of drugs reported increased with rising age. Restricted to potentially interacting drugs pairs with more than 10 reports (n = 704 reports, 1,111pDDI), the two most frequently identified pDDIs were (i) hyponatremias related to antidepressants and diuretics (n = 362, 32.6%) and (ii) bleeding events related to selective serotonin reuptake inhibitors (SSRI) and platelet aggregation inhibitors, anticoagulants or non-steroidal anti-inflammatory drugs (NSAIDs) (n = 295, 26.5%). After individual assessment of reports, bleeding events were found in 33.3% (14/42), 23.7% (45/190) and 17.4% (8/46) of reports related to SSRIs and anticoagulants, SSRIs and platelet aggregation inhibitors and SSRIs and NSAIDs. Hyponatremia was observed in 7.6% (22/289) of the reports related to antidepressants and diuretics. Well-known DDI still occur to a considerable amount in everyday clinical practice in psychiatric patients treated with psychiatric drugs and somatic medications. Special attention should be paid to older polymedicated patients.