For more than 60 years, succinylcholine is still being administered as the 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. However, it has many side effects as
well.
Postoperative myalgia (POM), with an incidence rate of about 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 non-depolarizing muscle
relaxants, benzodiazepines, magnesium sulfate, opioids, gabapentin, pregabalin and
nonsteroidal anti-inflammatory drugs have been tested, with varying degrees of success.
Free radicals are created as a consequence of ATP (adenosine triphosphate) production by the
mitochondria. These by-products are generally reactive oxygen species (ROS) as well as
reactive nitrogen species (RNS) that result from the cellular redox process. These species
play a dual role as both toxic and beneficial compounds. The delicate balance between their
two antagonistic effects is clearly an important aspect of life. At low or moderate levels,
ROS and RNS exert beneficial effects on cellular responses and immune function. At high
concentrations, they generate oxidative stress, a deleterious process that can damage all
cell structures. Muscle injuries might lead to the production of free radicals and further
cellular damage, triggered by lipid peroxidation and protein oxidation. Peroxidation of
membrane lipids leads to loss of membrane fluidity and elasticity, impaired cellular
functioning, and even cell rupture. The various direct products of lipid peroxidation, such
as malondialdehyde (MDA), isoprostanes, and 4-hydroxynonenal are considered among the most
important biomarkers of oxidative stress in tissues. Malondialdehyde is a reactive carbonyl
compound and is both mutagenic and carcinogenic. It reacts with DNA to form DNA adducts that
are believed to contribute significantly to cancers linked to lifestyle and dietary factors.
Protein oxidation can cause fragmentation at amino acid residues, formation of
protein-protein cross-linkages, and oxidation of the protein backbone which ultimately leads
to loss of function. Damaged proteins affect intracellular pathways and are contributing
factors to different disorders and diseases. Protein carbonyl (CO) groups are produced on
protein side chains during oxidation. High levels of protein CO groups have been observed in
rheumatoid arthritis, Alzheimer's disease, diabetes, sepsis and chronic renal failure.
Selenium is a well-recognized antioxidant which act s as a cofactor of antioxidant enzymes.
This essential element helps protect the body against free radicals causing damage to the
cells. Substantial evidence suggests that free radical production leads to increased oxygen
uptake over time. The indirect though significant impact of selenium supplements is to
protect the cells against oxidative stress and free radical production. Nature-made selenium
contains 200 mg of this element with a natural origin, high absorption capacity, and
prolonged retention. Selenium exerts its antioxidant effects through glutathione peroxidase.
Glutathione peroxidase is an enzyme containing four selenium-cofactors that catalyze the
breakdown of hydrogen peroxide and organic hydroperoxides. There are at least four different
glutathione peroxidase isozymes in animals. Glutathione peroxidase 1 is the most abundant and
is a very efficient scavenger of hydrogen peroxide, while glutathione peroxidase 4 is most
active with lipid hydroperoxides. The glutathione S-transferases show high activity with
lipid peroxides. These enzymes are at particularly high levels in the liver and serve in
detoxification metabolism.