Drug Utilization Patterns and Potential Drug–Drug Interaction Burden in Respiratory Prescriptions: A Real-World Community Pharmacy Study

Background: Respiratory disorders are frequently managed in community pharmacies and may involve complex multidrug regimens, particularly in asthma and chronic obstructive pulmonary disease (COPD). We aimed to characterize respiratory pharmacotherapy and moderate or major potential drug–drug interaction (DDI) risk using one index respiratory prescription per patient. Methods: We performed a retrospective observational secondary analysis of anonymized electronic prescription data from two Romanian community pharmacies (November 2022–October 2023). From a combined source dataset comprising prescriptions with at least two active substances, we selected records containing at least one eligible respiratory diagnosis. Demographics, diagnostic groups, active substances, therapeutic classes, medication burden, and potential DDIs were evaluated. Multivariable logistic regression identified factors independently associated with at least one moderate or major potential DDI. Results: The final cohort included 643 patients. Median age was 52 years [interquartile range 23.5–66.0], and 50.7% were female. Asthma was the most frequent diagnostic group (41.1%), followed by acute upper respiratory tract infections (19.8%) and COPD (15.4%). The most frequent therapeutic classes were inhaled and intranasal corticosteroids (54.0%), long-acting beta-2 agonists (46.7%), and anti-infectives (35.0%). At least one moderate or major potential DDI was identified in 28.0% of index prescriptions. In the fully adjusted multivariable model, each additional active substance was associated with higher potential DDI odds (odds ratio [OR] 2.42, 95% confidence interval [CI] 1.96–3.00), while cardiovascular or metabolic co-medication showed the strongest positive class-level association (OR 14.16, 95% CI 5.25–38.21). Conclusions: Respiratory prescriptions showed distinct diagnostic and therapeutic profiles. The highest prevalence of moderate or major potential DDIs among the major diagnostic groups was observed in COPD. Potential DDI risk was strongly associated with medication burden and cardiovascular/metabolic co-medication, supporting targeted community pharmacy medication review that considers both respiratory therapy and the broader pharmacotherapeutic regimen.