Usage
- Succinylcholine chloride is a depolarizing neuromuscular blocking agent indicated as an adjunct to general anesthesia to facilitate tracheal intubation and provide skeletal muscle relaxation during surgery or mechanical ventilation. It is also used in other procedures requiring brief relaxation such as endoscopy, orthopedic manipulations, and electroconvulsive therapy.
- Pharmacological Classification: Neuromuscular Blocking Agent, Depolarizing Muscle Relaxant.
- Mechanism of Action: Succinylcholine acts as an acetylcholine receptor agonist at the neuromuscular junction. It initially depolarizes the motor end-plate, causing transient muscle fasciculations. The persistent depolarization then prevents further muscle contraction, leading to flaccid paralysis.
Alternate Names
- Suxamethonium Chloride
- Suxamethonium
- Succinylcholine
- Sucostrin
- Scoline
- Anectine
- Quelicin
How It Works
- Pharmacodynamics: Succinylcholine depolarizes the motor end-plate at the neuromuscular junction, mimicking the action of acetylcholine but with a much longer duration. This sustained depolarization renders the postsynaptic membrane unresponsive to further stimulation by acetylcholine, resulting in flaccid paralysis.
- Pharmacokinetics:
- Absorption: Primarily administered intravenously (IV) or intramuscularly (IM). IV administration results in rapid onset of action (within 1 minute). IM administration has a slower onset (2-3 minutes).
- Metabolism: Rapidly hydrolyzed by plasma pseudocholinesterase (butyrylcholinesterase), an enzyme distinct from acetylcholinesterase.
- Elimination: The metabolites are primarily excreted renally.
- Mode of Action: Binds to nicotinic acetylcholine receptors at the motor end-plate, causing prolonged depolarization and preventing repolarization, thus blocking neuromuscular transmission.
- Receptor Binding: Agonist at nicotinic acetylcholine receptors.
- Elimination Pathways: Renal excretion of metabolites.
Dosage
Standard Dosage
Adults:
- Intubation/Short Procedures: 0.6 mg/kg IV (range: 0.3-1.1 mg/kg). Onset is typically within 1 minute, with a duration of 4-6 minutes.
- Continuous Infusion (Long Procedures): 2.5-4.3 mg/minute IV. Alternatively, intermittent IV boluses of 0.04-0.07 mg/kg can be given as needed.
Children:
- Infants and Small Children: 2 mg/kg IV (emergency intubation or immediate airway securing).
- Older Children and Adolescents: 1 mg/kg IV (emergency intubation or immediate airway securing).
- IM (if IV access unavailable): 3-4 mg/kg (maximum 150 mg total dose).
Special Cases:
- Elderly Patients: Start at the lower end of the dosing range due to potential for decreased hepatic, renal, or cardiac function.
- Patients with Renal Impairment: Normal single dose can be used in the absence of hyperkalemia. Multiple or larger doses should be avoided.
- Patients with Hepatic Dysfunction: Plasma cholinesterase levels may be reduced, requiring dosage adjustments.
- Patients with Comorbid Conditions: Use with caution in patients with cardiovascular disease, asthma, pulmonary impairment, burns, hyperkalemia, malignant hyperthermia, skeletal muscle myopathies, and upper motor neuron injury.
Clinical Use Cases
- Intubation: 0.6 mg/kg IV (standard dose), 1.5 mg/kg IV (rapid sequence intubation).
- Surgical Procedures: Continuous infusion (2.5-4.3 mg/minute) or intermittent boluses (0.04-0.07 mg/kg).
- Mechanical Ventilation: Dosage adjusted based on patient response and desired level of relaxation.
- Intensive Care Unit (ICU) Use: Continuous infusion adjusted based on patient need.
- Emergency Situations: 1-2 mg/kg IV.
Dosage Adjustments
- Adjust dosage based on patient response, duration of procedure, and any underlying medical conditions.
- Renal/hepatic dysfunction, metabolic disorders, or genetic polymorphisms affecting pseudocholinesterase activity require careful dose adjustments.
Side Effects
Common Side Effects
- Jaw rigidity
- Hypotension
- Muscle fasciculations (may cause postoperative pain)
- Respiratory depression (including apnea)
- Salivary gland enlargement
- Increased intraocular pressure
Rare but Serious Side Effects
- Malignant hyperthermia
- Hyperkalemia
- Cardiac arrhythmias (including bradycardia and tachycardia)
- Rhabdomyolysis
- Anaphylaxis
Long-Term Effects
- Postoperative muscle pain may persist.
Adverse Drug Reactions (ADR)
- Severe allergic reactions (anaphylaxis) requiring immediate intervention.
Contraindications
- Personal or familial history of malignant hyperthermia
- Skeletal muscle myopathies
- Known hypersensitivity to succinylcholine
- Hyperkalemia
- Acute phase of injury following major burns, multiple trauma, extensive denervation of skeletal muscle, or upper motor neuron injury (except when immediate airway securing is clinically necessary).
- Patients with atypical or deficient pseudocholinesterase.
Drug Interactions
- Antibiotics: Aminoglycosides (e.g., gentamicin, neomycin), clindamycin, colistimethate, polymyxins, lincomycin.
- Anesthetics: Inhalational anesthetics (e.g., isoflurane, desflurane, halothane).
- Other: Magnesium salts, lithium carbonate, quinidine, procainamide, lidocaine, beta-blockers, promazine, oxytocin, aprotinin, metoclopramide, terbutaline, cholinesterase inhibitors (e.g., echothiophate), certain antineoplastic drugs, oral contraceptives, glucocorticoids, monoamine oxidase inhibitors (MAOIs).
Pregnancy and Breastfeeding
- Pregnancy Safety Category: C (US FDA).
- Fetal Risks: Small amounts cross the placenta; repeated high doses or maternal atypical pseudocholinesterase may cause neonatal respiratory depression. While generally safe for single use during cesarean section, use caution and weigh benefits against risks.
- Breastfeeding: Excretion in breast milk is unknown. Exercise caution when administering to nursing mothers.
Drug Profile Summary
- Mechanism of Action: Depolarizing neuromuscular blocker, agonist at nicotinic acetylcholine receptors.
- Side Effects: Muscle fasciculations, respiratory depression, hypotension, malignant hyperthermia (rare), hyperkalemia (rare).
- Contraindications: Malignant hyperthermia history, myopathies, hyperkalemia, burns, trauma.
- Drug Interactions: Aminoglycosides, certain anesthetics, magnesium salts, cholinesterase inhibitors.
- Pregnancy & Breastfeeding: Use with caution. Category C.
- Dosage: Adults: 0.6 mg/kg IV; Children: 1-2 mg/kg IV. Adjustments needed for special populations.
- Monitoring Parameters: Respiratory rate, oxygen saturation, heart rate, blood pressure, muscle activity, serum potassium.
Popular Combinations
- Often used in conjunction with anesthetics (e.g., propofol, sevoflurane) to achieve rapid sequence intubation and muscle relaxation during surgical procedures.
Precautions
- General Precautions: Careful patient assessment, including history of allergies, neuromuscular disorders, and electrolyte imbalances.
- Specific Populations: Adjust dosage in elderly, renally/hepatically impaired, pregnant, and breastfeeding individuals. Exercise caution in children.
- Lifestyle Considerations: Patients should avoid alcohol and operating machinery until the drug’s effects have completely worn off.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Succinyl Choline Chloride?
A: Adults: 0.6 mg/kg IV for intubation/short procedures; 2.5-4.3 mg/minute IV infusion for longer procedures. Children: 1-2 mg/kg IV. IM administration (3-4 mg/kg, max 150 mg) if IV access unavailable. Dosage adjustments necessary in special populations.
Q2: How quickly does Succinyl Choline Chloride work?
A: IV administration: Onset within 1 minute. IM administration: Onset within 2-3 minutes.
Q3: What are the most serious side effects of Succinyl Choline Chloride?
A: Malignant hyperthermia, hyperkalemia, cardiac arrhythmias, anaphylaxis, rhabdomyolysis.
Q4: What are the contraindications to using Succinyl Choline Chloride?
A: Malignant hyperthermia history, myopathies, hyperkalemia, acute burns/trauma, atypical pseudocholinesterase.
Q5: Can Succinyl Choline Chloride be used in pregnant women?
A: Use cautiously; weigh benefits vs. risks. Single dose for cesarean section generally safe but repeated doses or maternal atypical pseudocholinesterase may lead to neonatal respiratory depression.
A: By plasma pseudocholinesterase (butyrylcholinesterase).
Q7: What drugs interact with Succinyl Choline Chloride?
A: Aminoglycosides, certain anesthetics, magnesium salts, cholinesterase inhibitors, among others. Refer to the Drug Interactions section for a complete list.
Q8: What are the monitoring parameters for patients receiving Succinyl Choline Chloride?
A: Respiratory rate, oxygen saturation, heart rate, blood pressure, muscle activity, and serum potassium levels should be closely monitored.
Q9: Can succinylcholine be used in patients with renal impairment?
A: A single normal dose can be administered in the absence of hyperkalemia. Multiple or larger doses should be avoided due to the risk of clinically significant increases in serum potassium.
Q10: What should be done if a patient experiences prolonged apnea after succinylcholine administration?
A: Provide controlled respiration (assisted ventilation) until spontaneous respiration returns. Suspect atypical pseudocholinesterase deficiency.
