Impact of Cytochrome P450 and P-gp-Mediated Drug Interactions in Patient Prescriptions at a Tertiary Care Hospital: A Cross-Sectional Follow-Up Study

Background: Drug interactions, especially those mediated by CYP450 enzymes and P-glycoprotein (P-GP), contribute significantly to medication errors and are often overlooked in clinical practice. Identifying and managing these interactions is vital for patient safety. This study aims to assess the prevalence of CYP450- and P-gp-mediated drug interactions in hospitalized prescriptions, including narrow therapeutic index drugs and patients with alcohol or smoking history, and to explore strategies to reduce clinically significant interactions. Materials and Methods: It is a cross-sectional observational study; the collected data are analysed for potential drug interactions using Micromedex, Drug Bank, and SuperCYP to identify which of the CYP450 enzymes and P-GP could be involved in the drug interactions, considering patients' personal habits and medical and medication-related information. Results: A total of 196 patients had the potential for a drug interaction, but about 29 had clinically significant drug interactions. Logistic regression was performed, and all the predictor variables for PDIs were statistically significant. The most frequent drug-drug, drug-alcohol, drug-smoking, drug-food, and clinically significant interactions mediated by CYP450 and P-GP interactions were tabulated. Conclusion: Our study discusses the importance of proactively identifying preventable drug interactions. Clinical pharmacists can significantly reduce adverse outcomes and enhance patient safety by designing tailored drug regimens based on biological and pharmaceutical factors and evidence-based prescribing.