Retrospective Analysis of Adverse Drug Reactions Reported in a Quaternary Care Centre

Background and Aims: Adverse drug reactions (ADRs) are noxious and unintended responses occurring at normal therapeutic doses and remain a major cause of morbidity in hospitalised patients. Systematic evaluation of ADR patterns and causality is essential to strengthen pharmacovigilance and improve medication safety. Objectives: To evaluate the pattern and causality of ADRs reported in a quaternary care hospital; to compare causality assessment using the Naranjo algorithm and the WHO-UMC scale; and to identify commonly implicated drug classes and patient demographics. Methods: A retrospective observational study was conducted using ADR reports submitted to the Clinical Pharmacy Department of a quaternary care hospital in Navi Mumbai between January 2022 and December 2024. Data from 221 ADR reports were analysed for demographics, suspected drugs, route of administration, severity, outcomes and causality assessment. Descriptive statistics were used. Results: Of 221 ADRs, females were slightly more affected than males, and patients aged 41–60 years accounted for the largest proportion. Antibiotics were the most frequently implicated drug class, followed by iron preparations and antineoplastic agents. The intravenous route was most associated with ADRs. The WHO-UMC scale categorised most reactions as probable, whereas the Naranjo algorithm classified the majority as possible. Most patients recovered completely with supportive management; no mortality was reported. Conclusion: ADRs continue to be an important cause of morbidity in hospitalised patients. Antibiotics and parenteral iron formulations were the leading contributors. Differences between causality assessment tools underscore the need for improved documentation and harmonised evaluation to strengthen institutional pharmacovigilance.