Postoperative sore throat (POST) is one of the most common complications following general anesthesia with endotracheal intubation, affecting patient comfort, delaying recovery, and reducing overall satisfaction with perioperative care. Although POST is usually self-limiting, its high incidence makes it an important target for preventive interventions.

Nebulized ketamine has emerged as a promising non-invasive strategy for reducing POST because of its local analgesic and anti-inflammatory effects mediated through N-methyl-D-aspartate (NMDA) receptor antagonism. Previous randomized trials and systematic reviews have demonstrated that nebulized ketamine can reduce both the incidence and severity of POST compared with placebo. However, most published studies have evaluated a single 50-mg dose, and the minimum effective dose remains uncertain.

This prospective, randomized, placebo-controlled, double-blind clinical trial aims to compare the efficacy and safety of two preoperative doses of nebulized ketamine (25 mg and 50 mg) with placebo in adult patients undergoing elective surgery under general anesthesia with endotracheal intubation. Participants aged 18-65 years with American Society of Anesthesiologists (ASA) physical status I or II will be randomly assigned in a 1:1:1 ratio to receive nebulized ketamine 25 mg, nebulized ketamine 50 mg, or nebulized normal saline 15 minutes before induction of anesthesia.

The primary outcome is the incidence of postoperative sore throat assessed at 2, 4, 6, 12, and 24 hours after surgery using a standardized four-point grading scale. Secondary outcomes include the severity of POST, postoperative pain intensity measured using the Visual Analog Scale (VAS), patient satisfaction, need for rescue analgesia, sedation assessed using the Ramsay Sedation Scale, and the incidence of adverse effects, including nausea, dizziness, and hallucinations.

The study hypothesizes that a lower dose of nebulized ketamine (25 mg) will provide comparable protection against postoperative sore throat to the conventional 50-mg dose while minimizing dose-related adverse effects. Identifying the minimum effective dose may improve the safety profile, optimize perioperative patient comfort, and support evidence-based recommendations for preventing postoperative sore throat after endotracheal intubation.