Intravenous dezocine for suppressing fentanyl-induced cough during general anesthesia induction: A potentially effective and clinically feasible method.

Sir,

Fentanyl is a most commonly used opioid during induction of general anesthesia (GA) due to its rapid onset, short duration of action, ease of titrability, cardiovascular stability, and intense analgesia.[12] Intravenous (IV) administration of fentanyl during induction of anesthesia commonly induces the cough reflex. The incidence of fentanyl-induced cough (FIC) varies between 28% and 80% in numerous studies.[2] This condition is usually benign, transient, and self-limited for most patients, but at times may be spasmodic, explosive, and life-threatening.[1] Although the mechanism of FIC is not clearly elucidated, various pharmacological, and nonpharmacological interventions such as using propofol, β2 agonist, pentazocine, lidocaine, dexmedetomidine, ketamine, dexamethasone, and huffing maneuver prior to induction, have been investigated to reduce the incidence of FIC during induction of anesthesia. However, these approaches which are tried are not uniformly effective.[12]

Dezocine is an opioid analgesic with mixed agonist-antagonist properties, a full agonist of κ-receptor and partial agonist of μ-receptor.[123] However, a molecular, clinical study showed higher antagonistic effects of dezocine for κ-receptor as compared to its agonistic properties.[3]

The efficacy of dezocine on postoperative pain, emergence agitation after anesthesia, neuropathic pain, and myoclonus induced by etomidate has been investigated.[34] Few studies examined the effect of dezocine on the prevention of FIC. In a study by Sun et al. has shown that IV administration of dezocine (0.1 mg/kg) 10 min prior to induction of GA was able to suppress FIC significantly compared to placebo.[2] Another study by Xu et al. aiming to investigate the effects of different doses of dezocine on FIC showed that IV dezocine with dose of 0.025, 0.05, 0.1 mg/kg effectively suppress FIC during anesthetic induction, with the effect being most marked for dezocine 0.1 mg/kg.[1]

Liu et al. evaluate the effects of dezocine on sufentanil-induced cough in patients during the induction of GA. The results of this study revealed that patients who received dezocine during GA induction had significantly lower incidence and the severity of a cough, as compared with patients who received normal saline.[5] Despite its potential benefit, it has been shown that dezocine increases the incidence of vomiting.[1] Although the exact FIC preventive mechanism of dezocine is not clearly explained, dezocine may reduce cough by activating κ receptors that in turn leads to antagonizing fentanyl-activated μ receptors. The probable mechanism of this alleviation could be the occupation of receptors responsible for cough through giving dezocine before fentanyl, which may halt any potential interaction.[135]

In sum, considering the results of the aforementioned studies, IV administration of dezocine may be recommended as a potentially effective, safe, and clinically feasible method for suppressing FIC during GA induction. However, further well-designed randomized clinical trials are required to delineate the effects and mechanisms of dezocine in FIC prevention during induction of GA; as well as, its safety, optimal doses, route of administration, and side effects.

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