Tehran University of Medical Sciences Archives of Anesthesiology and Critical Care 2423-5849 0 0 2025 12 15 1334 1334 Hagar Refaee Department of Anesthesia, Surgical Intensive Care, and Pain Management, Faculty of Medicine, Cairo University, Cairo, Egypt. Ahmed AL-Madawi Department of Anesthesia, Surgical Intensive Care, and Pain Management, Faculty of Medicine, Cairo University, Cairo, Egypt. Ahmed Nasr Department of Anesthesia, Surgical Intensive Care, and Pain Management, Faculty of Medicine, Cairo University, Cairo, Egypt. Mahmoud Ahmed Department of Anesthesia, Surgical Intensive Care, and Pain Management, Faculty of Medicine, Cairo University, Cairo, Egypt. Norhan Ali Department of Anesthesia, Surgical Intensive Care, and Pain Management, Faculty of Medicine, Cairo University, Cairo, Egypt. 2025 07 06 2025 08 18 Background: The objective of this work had been to identify the minimum effective and safest dosage of intrathecal hyperbaric prilocaine 2% in combination with 25 µg of fentanyl necessary for day-case lower abdominal and urologic procedures. Methods: This randomized, parallel-group, double-blind clinical study included 45 individuals, aged 65 to 80 years, of both sex, planned for elective day-case lower abdomen or urologic surgeries. Patients were randomly placed in three groups. All groups were administered 25 µg of fentanyl (0.5 mL) with intrathecal prilocaine 2%, with dosages of 30 mg (1.5 mL) for group P1, 40 mg (2 mL) for group P2, and 50 mg (2.5 mL) for group P3. Results: The time length of motor blockage and complete regression of sensory block were considerably prolonged in group P3 contrasted to groups P1 and P2. Intraoperative SBP and MAP were substantially elevated at 15, 30, 45, and 60 minutes in group P1 contrasted to group P3. The length of stay in the post-anaesthesia care unit (PACU) was markedly reduced in groups P1 and P2 compared to P3. Hypotension and bradycardia exhibited no significant differences across all groups Conclusion: In elderly individuals having lower abdominal and urologic surgery, a low dose of prilocaine combined with fentanyl yields a reduced duration of block and a shorter PACU stay, along with improved hemodynamic stability, compared to a higher dose of prilocaine with fentanyl. https://aacc.tums.ac.ir/index.php/aacc/article/view/1334