UTILIZATION AND ADVERSE EFFECT PROFILE OF PROPOFOL, MIDAZOLAM, FENTANYL, AND ONDANSETRON IN THE PERIOPERATIVE PERIOD: A PROSPECTIVE OBSERVATIONAL STUDY

Abstract

Objectives: The objective of this study was to assess the perioperative utilization pattern of propofol, midazolam, fentanyl, and ondansetron and to describe the frequency and profile of associated adverse events among adult surgical patients. Methods: This prospective observational study included 100 adult patients undergoing elective or emergency surgery from December 2025 to March 2026. Demographic characteristics, American Society of Anesthesiologists (ASA) physical status, anesthetic technique, study-drug exposure, indication, timing of administration, and perioperative adverse events were recorded using anesthesia charts, monitoring sheets, drug administration records, and direct clinical observation. Data were analyzed using descriptive statistics, and selected categorical associations were assessed as exploratory analyses. Results: The mean age of the patients was 41.8±13.6 years, and 68.0% were women. General anesthesia alone was used in 58.0% of patients, spinal anesthesia in 26.0%, monitored anesthesia care in 9.0%, and combined general-regional anesthesia in 7.0%. Fentanyl was the most frequently used study drug (88.0%), followed by propofol (84.0%), ondansetron (81.0%), and midazolam (76.0%). Propofol was mainly used for induction, midazolam for premedication or anxiolysis, fentanyl for induction adjunct and intraoperative analgesia, and ondansetron for antiemetic prophylaxis. At least one adverse event or clinically relevant drug-associated effect was recorded in 38.0% of patients. The common events were hypotension, post-operative nausea or vomiting, injection pain, bradycardia, excessive sedation or delayed recovery, dizziness, and respiratory depression or desaturation. Higher observed adverse-event proportions were noted in ASA III patients, longer procedures, general or combined anesthesia, and exposure to three or more study drugs; however, these findings were exploratory. No life-threatening adverse drug reaction was documented. Conclusion: Propofol, fentanyl, midazolam, and ondansetron were commonly used according to their usual perioperative indications. Most observed adverse events were expected, early, and manageable with routine perioperative monitoring. The findings support careful dose titration, structured documentation, and periodic drug-utilization audits in anesthesia practice.