Safety Profile Evaluation of Narrow Therapeutic Index Drugs in TertiaryCare Teaching Hospital

Introduction: Narrow therapeutic index (NTI) drugs have a small margin between effective and toxic doses, so minor changes in blood levels can cause therapeutic failure or toxicity, leading to significant drug-related problems. The study aims to assess drug-related problems (DRPs) linked to NTI drugs at Government General Hospital, Kadapa, by screening prescriptions, classifying DRPs using Pharmaceutical Care Network Europe (PCNE) v9.0, implementing interventions to reduce them, and calculating drug risk ratios to determine each drug’s contribution. Methods: A six-month prospective observational study (June–November 2023) included 110 inpatients prescribed at least one NTI drug. Data from standardized forms and hospital records were analyzed, with DRPs identified using PCNE v9.0, Micromedex, and WHO adverse drug reaction (ADR) scales. Results: Of 110 patients, 48 (43.6%) had DRPs, mainly males (60.4%) aged 31–60 years. Treatment effectiveness issues dominated (74.5%), with major interactions from digoxin, telmisartan, and heparin. Heparin showed the highest drug risk ratio (0.53), indicating significant safety concerns. Discussion: Findings highlight the high DRP risk from multiple NTI drug prescriptions, particularly heparin and digoxin. Results align with existing research and underscore the role of clinical pharmacy in DRP prevention. Drug risk ratio offers a quantitative tool for prioritizing monitoring. Conclusion: In our study, the most common DRPs observed were related to the drug use process. Heparin and digoxin were found to be high-risk drugs, according to study results. Hence, special observation and monitoring from physicians and other health professionals are needed for the prescriptions with NTI drugs.