Ondansetron Versus Lidocaine for Preventing Pain on Propofol Injection.

This is a prospective, single-center, randomized, double-blind controlled trial involving patients scheduled for elective surgery requiring general anesthesia with propofol induction. Participants are randomly assigned to one of three groups: the ondansetron group (8 mg IV), the lidocaine group (40 mg IV), or the control group (0.9% normal saline placebo). Study medications are administered intravenously over 5 minutes, ending 1 minute before anesthetic induction. the goal: To assess the efficacy of intravenous ondansetron versus lidocaine and placebo in reducing the incidence and intensity of pain associated with propofol injection in patients undergoing general anesthesia.

Inclusion Criteria: * The study included patients who met all of the following criteria: Aged 18 years or older; Classified as ASA physical status I-III (Appendix 1); Provided written informed consent to participate in the study; Scheduled for elective surgery requiring general anesthesia with propofol induction. Exclusion Criteria: * Patients were not eligible for inclusion if they: Had received analgesics or antiemetics within 12 hours before surgery; Had communication difficulties or were unable to assess pain adequately (e.g., language barrier, dementia, impaired consciousness); Had a known allergy to ondansetron, lidocaine, or propofol; Did not receive propofol for anesthetic induction; Were pregnant or breastfeeding; Suffered from chronic pain or regularly used opioid medications; Did not have a 20-gauge intravenous catheter inserted on the dorsum of the hand; Declined participation in the study. Patients were excluded from the study if they experienced any complication during anesthetic induction, including: Anaphylactic shock or allergic reaction to study medications; Hemodynamic or respiratory instability. Patients who subsequently withdrew their consent were also excluded from the study.