succinylcholine

Succinylcholine is a skeletal muscle relaxant used while performing medical procedures under general anesthesia, including tracheal intubation, mechanical ventilation, and surgeries. Succinylcholine belongs to a class of medication known as depolarizing neuromuscular blockers. Succinylcholine temporarily paralyzes the skeletal muscles preventing their contraction and movement during medical procedures.

Succinylcholine works by blocking the activity of acetylcholine, the chemical messenger (neurotransmitter) that nerve cells (neurons) release at the neuromuscular junction to make muscles contract. Neuromuscular junction, also known as motor end plate, is the site of communication between a nerve fiber and a muscle cell.

Succinylcholine binds to acetylcholine receptors in the motor end plate and depolarizes the muscle fiber membranes, generating an action potential. It continues to bind to the receptors preventing further neurotransmission, leading to muscle paralysis. The initial depolarization causes muscle twitches (fasciculations) before muscle paralysis sets in progressively, starting with the face, glottis, rib muscles, diaphragm and eventually in all the skeletal muscles.

Succinylcholine’s effects are rapid, causing paralysis within 60 seconds and a single intravenous administration lasts for 4-6 minutes, which makes it particularly useful for short procedures. Succinylcholine has no effects on consciousness or pain, and is used as an adjunct to anesthetic and analgesic drugs used during general anesthesia.

Succinylcholine has no direct effect on smooth muscles and cardiac muscles, however, it can disturb the heart rhythm because it stimulates the autonomous nervous system. Additionally, depolarization causes influx of sodium ions into muscle cells and release of potassium ions. The resultant increase in blood potassium levels can lead to irregular heart rhythm (dysthymia) or cardiac arrest, particularly in individuals with certain muscle diseases or pre-existing high potassium levels (hyperkalemia).

• Succinylcholine should be administered only by medical personnel skilled in the management of artificial respiration and only when facilities are available for instant tracheal intubation and adequate ventilation.
• Do not administer succinylcholine before inducing unconsciousness, to avoid distress to the patient, except in emergency situations
• Do not administer succinylcholine to patients who have:
  • Known hypersensitivity to succinylcholine or any of its components
  • Skeletal muscle diseases (myopathies) with elevated serum creatine kinase
  • Dangerously high temperature (malignant hyperthermia) or a history of malignant hyperthermia
• Succinylcholine administration to seemingly healthy pediatric patients has been reported to have resulted in acute muscle breakdown (rhabdomyolysis) with hyperkalemia followed by ventricular dysrhythmias, cardiac arrest and death; the patients were subsequently found to have undiagnosed skeletal muscle myopathy, most often Duchenne muscular dystrophy, a genetic muscle wasting disease
  • When a healthy appearing child develops cardiac arrest after administration of succinylcholine for no apparent reason, hyperkalemia treatment should be instituted immediately, and hyperthermia treatment, if required
  • Use succinylcholine in pediatric patients for only emergency intubation or instances where immediate securing of the airway is necessary, since there may be no signs or symptoms to recognize which patients are at risk
• Do not administer succinylcholine to patients after the acute phase of injury from major burns, multiple trauma, extensive denervation of skeletal muscle or upper motor neuron injury; may result in severe hyperkalemia and cardiac arrest, the risk of which increases over time and may peak at 7-10 days after the injury
• Exercise extreme caution in administering succinylcholine in the following circumstances because of the great risk for severe hyperkalemia and cardiac arrest:
  • Patients suffering from electrolyte imbalances
  • Patients with massive digitalis toxicity
  • During the acute phase of injury from major burns, multiple trauma, extensive denervation of skeletal muscle or upper motor neuron injury
  • Patients with chronic abdominal infection, subarachnoid hemorrhage, degenerative or dystrophic neuromuscular disease, and conditions that may cause degeneration of central and peripheral nervous systems
• Use succinylcholine with extreme caution in patients with known or suspected deficient activity of plasma cholinesterase, an enzyme that metabolizes succinylcholine; deficiency in plasma cholinesterase may cause neuromuscular blockade effects to persist for a prolonged period; cholinesterase deficiency may be genetic or acquired
• Severe, sometimes life-threatening and fatal, anaphylactic reactions have been reported with succinylcholine; readiness for immediate emergency treatment is essential
• Succinylcholine administration has been associated with acute onset of malignant hyperthermia, a potentially fatal hypermetabolic state of skeletal muscle with high temperature and other symptoms; the risk increases with concomitant use of volatile anesthetics
  • Patient should be monitored closely for development of malignant hyperthermia
  • At the first sign of malignant hyperthermia, anesthesia should be discontinued and appropriate treatment instituted
• Intravenous succinylcholine can slow down the heartbeat (bradycardia) and lead to cessation of cardiac electrical impulse (asystole), and the risk is higher with a second dose, particularly in children; pretreatment with atropine may reduce the occurrence of bradycardia
• Succinylcholine can increase intraocular pressure; avoid administering to patients with conditions such as narrow angle glaucoma or penetrating eye injury unless potential benefit outweighs potential risk
• Succinylcholine may cause a transient increase in intracranial pressure; however, induction of adequate anesthesia prior to the administration will minimize this effect
• Use with caution in patients with fractures or muscle spasm because initial muscle fasciculations may cause additional trauma
• Succinylcholine may increase intragastric pressure, which could result in regurgitation and possible aspiration of stomach contents; monitor the patient closely

Common side effects of succinylcholine include:

• Postoperative muscle pain
• Jaw rigidity
• Muscle twitch (fasciculation)
• Respiratory depression
• Cessation of breathing (apnea)
• Low or high blood pressure (hypotension or hypertension)
• Irregular heart rhythms (cardiac arrhythmias)
• Slow or rapid heartbeat (bradycardia or tachycardia)
• Cardiac arrest
• Increase in intraocular pressure (IOP)
• High blood potassium levels (hyperkalemia)
• Severe life-threatening drug reaction with excessively high temperature (malignant hyperthermia)
• Salivary gland enlargement
• Excessive salivation
• Rash
• Hypersensitivity reactions
• Severe allergic reaction (anaphylaxis)
• Breakdown of muscle tissue (rhabdomyolysis)
• High blood level of myoglobin, a type of muscle protein (myoglobinemia)
• High myoglobin level in the urine (myoglobinuria)
• Acute kidney failure due to myoglobinuria

This is not a complete list of all side effects or adverse reactions that may occur from the use of this drug.

Call your doctor for medical advice about serious side effects or adverse reactions. You may also report side effects or health problems to the FDA at 1-800-FDA-1088.

Injectable solution

• 20 mg/mL
• 100 mg/mL

Neuromuscular blockade

Adult:

Load

• 0.3-1.1 mg/kg intravenously (IV) for 1 dose, OR
• 3-4 mg/kg intramuscularly (IM) for 1 dose
• Short Procedures: usually 0.6 mg/kg IV injection

Maintenance for Prolonged Procedures

• 0.04-0.07 mg/kg intravenously (IV) every 5-10 minutes as needed OR
• 2.5 mg/min IV infusion

Pediatric:

Load

• Infants and small children: 2 mg/kg intravenously (IV) for 1 dose
• Older children and adolescents: 1 mg/kg IV for 1 dose
• 3-4 mg/kg deep intramuscularly (IM) for 1 dose; not to exceed 150 mg total dose (no adequate IV)

Maintenance

• 0.3-0.6 mg/kg intravenously (IV) every 5-10 minutes as needed

Dosage considerations

• The solution contains 1% benzyl alcohol
• Prior administration of a "defasciculating" dose of nondepolarizing neuromuscular blocker (such as 0.01 mg/kg IV vecuronium) will prevent muscular fasciculations that may increase intracranial pressure/intraocular pressure (ICP/IOP)
• Adequate ventilatory support mandatory may experience increased sensitivity with electrolyte disorders (hypermagnesemia, hypokalemia, hypocalcemia)

Administration

• The dose should be calculated based on ideal body weight
• For intravenous or intramuscular use only

• Succinylcholine overdose may lead to neuromuscular block for a longer time than required for surgery and anesthesia.
• Symptoms include skeletal muscle weakness, decreased respiratory reserve, low tidal volume, or cessation of breathing.
• Treatment includes maintaining a patent airway and providing respiratory support until normal respiration is restored in the patient.

Inform your doctor of all medications you are currently taking, who can advise you on any possible drug interactions. Never begin taking, suddenly discontinue, or change the dosage of any medication without your doctor’s recommendation.

• Succinylcholine has no known severe interactions with other drugs.
• Succinylcholine has serious interactions with at least 28 different drugs.
• Succinylcholine has moderate interactions with at least 182 different drugs.
• Succinylcholine has mild interactions with at least 49 different drugs.

The drug interactions listed above are not all of the possible interactions or adverse effects. For more information on drug interactions, visit the RxList Drug Interaction Checker.

It is important to always tell your doctor, pharmacist, or health care provider of all prescription and over-the-counter medications you use, as well as the dosage for each, and keep a list of the information. Check with your doctor or health care provider if you have any questions about the medication.

• There are no studies on succinylcholine’s use during pregnancy; it is not known if it can cause fetal harm; use only if clearly needed and benefits outweigh potential risks
• It is not known if succinylcholine is excreted in human milk; use caution following succinylcholine administration to a nursing mother