Suppressing Effect of Dextromethorphan or Clonidine on Fentanyl- Induced Coughing: A Double- Blind, Prospective, Randomized Placebo- Controlled Study

Abstract

Background: Various medications have been examined to reduce fentanyl-induced cough. We studied the efficacy and safety of premedication with dextromethorphan or clonidine versus placebo prior to intravenous fentanyl injection on the cough reflex. Methods and Materials: In a randomized double-blind placebo controlled trial, 360 adult patients of American Society of Anesthesiologists physical status I-II, scheduled for elective surgery under general anesthesia were randomly allocated into three groups receiving clonidine (0.2 mg tablet orally),dextromethorphan (15 mg orally), or placebo 60 minutes before induction of anesthesia. The incidence of cough was recorded for 1 minute after fentanyl injection and graded as none (0), mild (1–2), moderate (3–5), and severe (>5 cough). Seventy three (20.3%) exhibited vigorous cough attacks during intravenous fentanyl administration. Results: The overall incidence of coughing in clonidine group (15.0%) and dextromethorphan (11.7%) group was lower than the placebo group (34.2%). Also, 3.3% of cases in the clonidine group and none of the patients in the dextromethorphan suffered from severe coughing, while 8.3% of the cases in the placebo group considered to have severe cough. Pretreatment with clonidine or dextromethorphan was positively associated with reduced incidence of fentanyl-induced cough after adjustment for potential confounders. Vital signs were all significantly lower following clonidine administration compared to both pretreatment regimens including dextromethorphan and placebo before and after intravenous fentanyl injection. Conclusion: Administering dextromethorphan or clonidine reduces the incidence of fentanyl-induced cough with better haemodynamic stability following the use of clonidine than dextromethorphan.