Objective: Endotracheal intubation can elicit significant haemodynamic responses, posing risks for patients with cardiovascular conditions. Clonidine, an alpha-2 adrenergic agonist, is used to mitigate these responses, but the optimal dosing is uncertain. This study compares the efficacy and safety of two doses of oral clonidine, 100 μg and 150 μg, administered 90 min before surgery. Methods: Sixty patients aged 18–55 y, classified as ASA physical status I or II and scheduled for elective lower abdominal surgeries, were randomly assigned to two groups. Group A received 100 μg of oral clonidine, and Group B received 150 μg. Haemodynamic parameters-heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP)-were recorded at baseline, during induction, immediately after intubation, and at intervals up to 15 min post-intubation. Side effects and the need for rescue analgesia were also assessed. Results: Group A demonstrated significantly lower SBP and HR at induction and during the immediate post-intubation period compared to Group B (p < 0.05). No significant differences were observed in DBP and MAP at most time points. The incidence of hypotension was higher in Group B but not statistically significant. Group B required significantly less rescue analgesia postoperatively (p < 0.001). Conclusion: A 100 μg dose of oral clonidine is more effective in attenuating haemodynamic responses during endotracheal intubation compared to a 150 μg dose. While the higher dose offers improved postoperative analgesia, it does not enhance haemodynamic stability and may increase the risk of hypotension.
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