Duloxetine for Succinylcholine-induced Postoperative Myalgia
Status:
Completed
Trial end date:
2019-11-30
Target enrollment:
Participant gender:
Summary
For >60 years, succinylcholine is still being administered as a selective relaxant for rapid
sequence intubation by anesthesiologists in many countries. It has been shown to possess
unique features such as low cost, fast-acting, short half-life, safe metabolites, and causing
excellent muscle relaxation for intubation. It has many side effects as well. Postoperative
myalgia (POM), with an incidence rate of ~41%-92%, is one of the most common side effects of
this drug and can take several days to cause significant discomfort in patients. However, its
effect is felt more in the throat, neck, shoulder, and abdominal muscles and is common among
patients with outpatient surgery. Due to its unknown real context of pathogenesis and in an
effort to reduce the incidence and severity of succinylcholine-induced myalgia, various
medications including nondepolarizing muscle relaxants, benzodiazepines, magnesium sulfate,
opioids, gabapentin, and nonsteroidal anti-inflammatory drugs have been tested, with varying
degrees of success.
Duloxetine is an US Food and Drug Administration-approved analgesic used for various pain
syndromes, including diabetic peripheral neuropathy and fibromyalgia. The underlying
mechanism for duloxetine against these pain syndromes remains unclear, but it may involve
three major central nervous system (CNS) targets: (1) serotonin transporter (Ki, 4.6 nM), (2)
norepinephrine transporter (Ki, 16 nM), and (3) dopamine transporter (Ki, 370 nM). In the
past, the antidepressant action was often thought to be the primary mechanism for its
analgesic efficacy. This theory was addressed later by "Path Analysis," and the result showed
that duloxetine affects pain directly rather than indirectly through mood improvement. In
addition to these multiple CNS targets, duloxetine, like the antidepressant amitriptyline and
the local anesthetic bupivacaine, blocks voltage-gated Na+ channels. Because neuronal Na+
channels are present in both CNS and peripheral nervous systems, such a finding expands the
possible analgesic action and locus of duloxetine.