The Magnitude of the Warfarin-Amiodarone Drug-Drug Interaction Varies With Renal Function: A Propensity-Matched Cohort Study

Risk of Fractures With Concomitant Use of Calcium Channel Blockers and Selective Serotonin Reuptake Inhibitors

BACKGROUND

Despite their frequent concurrent use, little is known about the concomitant use of calcium channel blockers (CCBs) and selective serotonin reuptake inhibitors (SSRIs) on fracture risk. We compared risk of fractures in patients concomitantly treated with CCBs and SSRIs versus CCB-only users. We compared risk of fractures among concomitant CCB-SSRI users initiating cytochrome P450 3A4 (CYP3A4)-inhibiting SSRIs versus non-CYP3A4 inhibiting SSRIs.

METHODS

This retrospective cohort study used IBM MarketScan commercial claims and Medicare Supplemental database (2007-2019). We included adults diagnosed with hypertension and depression, newly initiating SSRIs while being treated with CCBs (ie, concomitant CCB-SSRI users) and those who did not (ie, CCB-only users). Primary outcome was the first occurrence of any fracture. We used stabilized inverse probability of treatment weighting (sIPTW) based on propensity scores to balance baseline risk between groups. Cox proportional hazard regression modeling was used to compare fracture risk.

RESULTS

We identified 191 352 concomitant CCB-SSRI and 956 760 CCB-only users (mean age = 56 years, 50.1% males). After sIPTW, compared with CCB-only users, CCBs-SSRIs users had a higher risk of fractures (hazard ratio [HR]: 1.43, 95% confidence interval [CI]: 1.22-1.66). No difference in the risk of fractures between concomitant users of CCB-CYP3A4-inhibiting SSRIs and those of CCB-non-CYP3A4 inhibiting SSRIs (HR: 1.10, 95% CI: 0.87-1.40) was observed.

CONCLUSION AND RELEVANCE

Short-term concomitant CCB-SSRI use was associated with increased fracture risk. Concomitant CCBs and CYP3A4-inhibiting SSRIs compared with CCBs and non-CYP3A4 inhibiting SSRIs use was not associated with increased risk.

Drug–Drug Interactions with Oral Anticoagulants as Potentially Inappropriate Medications: Prevalence and Outcomes in Elderly Patients in Primary Care and Hospital Settings

Direct oral anticoagulants and vitamin K antagonists are considered as potentially inappropriate medications (PIM) in several situations according to Beers Criteria. Drug–drug interactions (DDI) occurring specifically with these oral anticoagulants considered PIM (PIM–DDI) is an issue since it could enhance their inappropriate character and lead to adverse drug events, such as bleeding events. The aim of this study was (1) to describe the prevalence of oral anticoagulants as PIM, DDI and PIM–DDI in elderly patients in primary care and during hospitalization and (2) to evaluate their potential impact on the clinical outcomes by predicting hospitalization for bleeding events using machine learning methods. This retrospective study based on the linkage between a primary care database and a hospital data warehouse allowed us to display the oral anticoagulant treatment pathway. The prevalence of PIM was similar between primary care and hospital setting (22.9% and 20.9%), whereas the prevalence of DDI and PIM–DDI were slightly higher during hospitalization (47.2% vs. 58.9% and 19.5% vs. 23.5%). Concerning mechanisms, combined with CYP3A4–P-gp interactions as PIM–DDI, were among the most prevalent in patients with bleeding events. Although PIM, DDI and PIM–DDI did not appeared as major predictors of bleeding events, they should be considered since they are the only factors that can be optimized by pharmacist and clinicians.

Magnitude of Drug–Drug Interactions in Special Populations

Drug–drug interactions (DDIs) are one of the most frequent causes of adverse drug reactions or loss of treatment efficacy. The risk of DDIs increases with polypharmacy and is therefore of particular concern in individuals likely to present comorbidities (i.e., elderly or obese individuals). These special populations, and the population of pregnant women, are characterized by physiological changes that can impact drug pharmacokinetics and consequently the magnitude of DDIs. This review compiles existing DDI studies in elderly, obese, and pregnant populations that include a control group without the condition of interest. The impact of physiological changes on the magnitude of DDIs was then analyzed by comparing the exposure of a medication in presence and absence of an interacting drug for the special population relative to the control population. Aging does not alter the magnitude of DDIs as the related physiological changes impact the victim and perpetrator drugs to a similar extent, regardless of their elimination pathway. Conversely, the magnitude of DDIs can be changed in obese individuals or pregnant women, as these conditions impact drugs to different extents depending on their metabolic pathway.