Drug-Drug Interactions in the General Ward of an Iranian Hospital and Clinical Pharmacists' Intervention: A Cross-Sectional Study

Hospitalized patients frequently receive multiple medications, increasing the potential for DDIs, which may result in increased morbidity, length of hospital stay, and healthcare costs. Clinical pharmacists play an essential role in detecting, preventing, and managing DDIs as part of the multidisciplinary care team^[1][2].

A cross-sectional study was conducted in the general ward of a 200-bed Iranian hospital. All adult inpatients (≥15 years) with at least two prescribed drugs were enrolled over a one-year period. Prescriptions were analyzed using standard DDI references (Lexicomp, Drug Interaction Facts, Drugs.com)^[3][4].

Clinical pharmacists reviewed all detected interactions, categorized them by severity, and intervened by providing feedback to the prescribing physicians for moderate or major DDIs.

Prevalence and Severity of DDIs

·        Total patients analyzed: 205

·        Total DDIs identified: 507

·        Prevalence of DDIs among prescriptions: 20.3%–24.7%

·        Severity breakdown:

o   Class C (monitor therapy): 81.9%

o   Class D & X (avoid or modify regimen): 17%

o   Major (potentially life-threatening): 10.8%

o   Moderate: 43.8%

o   Mild: 45.3%^[3][1][4]

Frequent Drug Pairs Involved in DDIs

Risk Factors for DDIs

·        Polypharmacy: Number of drugs per patient was a strong predictor; ≥7 drugs led to an odds ratio of 0.048 for DDI occurrence^[5].

·        Age: DDIs were significantly more frequent in patients ≥60 years.

·        Gender: Higher DDI prevalence among women.

·        Comorbidities: Cardiovascular diseases were associated with severe DDIs.

·        Length of Hospitalization: Longer stays increased DDI risk.

Impact of Clinical Pharmacists' Interventions

·        Pharmacist feedback reduced the DDI rate from 9.3% to 6.4% in further audits

·        Most frequently accepted interventions included dose adjustments, drug substitutions, or enhanced monitoring.

·        Acceptance rate for pharmacist recommendations: 62–74%

·        Interventions led to lower occurrences of major or moderate DDIs and improved physician awareness^[1][2][5].

Patterns and Clinical Implications

·        A significant proportion of hospital inpatients encounter potentially serious DDIs.

·        Most DDIs involved cardiovascular, anticoagulant, and central nervous system drugs.

·        Polypharmacy in elderly patients particularly increases DDI risk.

·        Systematic pharmacist-led DDI detection and intervention can reduce frequency and severity of adverse interactions, significantly improving patient safety.

Table: Summary of DDI Risk and Outcomes Before and After Pharmacist Intervention

Preventive Strategies

·        Physician-pharmacist communication

·        Routine prescription review by clinical pharmacists

·        Computerized DDI checking systems

·        Prescription audit and feedback loops

Figure 1: Proportion of DDI Severity in General Ward Patients

(Bar chart representation)

·        Mild: 45%

·        Moderate: 44%

·        Major: 11%

Figure 2: DDI Rate by Number of Prescribed Drugs

(Line graph showing exponential increase in DDI rate with ≥7 drugs prescribed)

DDIs are a common and actionable patient safety issue in Iranian hospital wards. Collaboration between clinical pharmacists and prescribers, along with continued education and prescription review, is effective in significantly reducing the incidence and severity of clinically important DDIs in hospitalized patients^[1][2][5].

Acknowledgements

No conflicts of interest declared. This review is intended for academic and clinical research purposes only.

1.      Ala, Shahram, et al. "Role of Pharmacist in Reducing the Rate of Drug Interactions; An Experience from North of Iran." Journal of Clinical Pharmacy, vol. 14, no. 7, 2020, pp. 133–143.

2.      Shafiekhani, M., et al. "Impact of Clinical Pharmacist's Interventions on Potential Drug–Drug Interactions in CCU and Cardiac Surgery Units." Journal of Research in Pharmacy Practice, vol. 8, no. 4, 2019, pp. 219–225.

3.      Sadeqian, F., et al. "Prevalence of Potential Drug Interactions in an Iranian General Hospital." Indian Journal of Pharmaceutical Sciences, vol. 74, no. 1, 2012, pp. 75–79.

4.      Aghajani, M. H., et al. "Potential Drug–Drug Interactions in Post-CCU of a Teaching Hospital in Tehran, Iran." Iranian Journal of Pharmaceutical Research, vol. 12, no. 4, 2013, pp. 773–779.

5.      Dialnet. "Drug-Drug Interactions in General Ward in an Iranian Hospital and Clinical Pharmacists' Intervention: A Cross-Sectional Study." 2020.