Succinylcholine (Anectine)

Emergency & Prehospital

• Rapid sequence intubation (RSI): paralysis for emergency tracheal intubation. It goes in after the induction agent, and only when nothing rules it out (see RSI)
• Emergency pediatric intubation: the label keeps pediatric use for emergency intubation or immediate airway securing (e.g., laryngospasm, difficult airway, full stomach). The boxed warning explains why it is this strict
• Paralysis without IV access: no usable vein? Use the IM route.

ED / ICU / Transport

• Intubation in the ED and ICU: when you want a short paralysis and the hyperkalemia and malignant hyperthermia (MH) screen is negative, this is the alternative to rocuronium

Other Uses

• Adjunct to general anesthesia and brief relaxation during mechanical ventilation (FDA-labeled): anesthesia teams manage it. For sustained paralysis, they reach for a nondepolarizing agent
• Electroconvulsive therapy (ECT): it blunts the motor convulsion during ECT anesthesia. Anesthesia manages it

Available Forms

• 20 mg/mL in 10 mL (200 mg) multiple-dose vial: Anectine, Quelicin and generics. Most EMS and transport services carry this one. Multiple-dose vials usually contain paraben preservatives.
• Prefilled single-dose syringes, 20 mg/mL: 100 mg/5 mL and 200 mg/10 mL (generic); preservative-free, discard the unused portion (manufacturer labeling)
• Appearance: clear, colorless and acidic (pH 3–4.5). Cloudy or discolored? Do not use it.

Adult Dosing

Pediatric Dosing

In children, bradycardia is common after a first dose. Under AHA/AAP PALS 2025, if atropine is given as premedication before emergency intubation, 0.02 mg/kg IV/IO with no minimum dose may be considered. Dosing by weight is covered in weight-based dosing.

Preparation & Administration

• Dilution: none for IV or IM bolus; give the 20 mg/mL solution undiluted.
• Push rate: rapid IV push, immediately after the induction agent; flush the line.
• Sequence: never before unconsciousness unless there is no alternative in an emergency (label); draw up post-intubation sedation and analgesia first.
• Line: do not mix with or push into alkaline solutions with pH above 8.5 (e.g., barbiturates such as methohexital).
• IO: not a labeled route; use only where local protocol allows.
• Infusion (anesthesia only): dilute to 1–2 mg/mL in D5W or NS, refrigerate, use within 24 hr; pump and nerve stimulator required.

Contraindications

• Known or suspected genetic susceptibility to MH: personal or family history of MH, or a known RYR1 or CACNA1S variant
• Skeletal muscle myopathies: e.g., Duchenne or Becker muscular dystrophy
• After the acute phase of major burns, multiple trauma, extensive denervation or upper motor neuron injury (spinal cord injury, stroke): the risk builds over time and usually peaks 7–10 days after injury. The exact onset is unknown. The 48-hr window considered safe applies to burns only. After denervation or spinal cord injury, a detectable K⁺ rise can appear within 6 hr. Receptor spread starts by about 48 hr, and K⁺ can reach critical levels by 72 hr. No evidence-based cutoff exists. Many protocols avoid succinylcholine after about 24 hr, or when the injury timing is unclear. Use rocuronium
• Known hypersensitivity to succinylcholine

Precautions

• Other hyperkalemia risks: prolonged immobility or critical illness, Guillain-Barré syndrome, botulism, ALS, multiple sclerosis, subarachnoid hemorrhage, chronic abdominal infection, rhabdomyosarcoma. Avoid it, or check that K⁺ is normal first.
• Existing hyperkalemia or digitalis toxicity: arrhythmia and arrest risk (label). On its own, renal failure with a normal K⁺ is not a contraindication.
• Reduced plasma cholinesterase: not recommended (label). Paralysis can run long. Inherited variants (see Special Populations) or acquired causes: pregnancy, severe liver or kidney disease, malignant tumors, infections, burns, anemia, decompensated heart disease, peptic ulcer, myxedema, some drugs.
• Bradycardia: children after a first dose, any patient after a second dose.
• Penetrating eye injury, narrow-angle glaucoma: intraocular pressure rises. Use it only when the benefit outweighs the risk. Intracranial pressure rises briefly, and adequate induction keeps that rise small.
• Prior anaphylaxis to any neuromuscular blocker: cross-reactivity has been reported.
• Fractures, muscle spasm; hypokalemia or hypocalcemia: fasciculations can add to the injury. Low K⁺ or Ca²⁺ lengthens the block.

Hold / Reassess If

• No airway rescue plan, suction, bag-mask, supraglottic airway or surgical airway kit at hand
• K⁺ above the normal range, or peaked T waves or a wide QRS on the monitor: use rocuronium
• Positive screen for burns, crush, denervation, myopathy, prolonged immobility or MH history: use rocuronium

Common

• Fasciculations before paralysis, and postoperative muscle pain
• Small serum K⁺ rise in healthy patients. The rise is larger in at-risk patients (see Contraindications)
• Bradycardia: common in children after 1.5 mg/kg. In adults, it mostly follows repeat doses.
• Tachycardia, hypertension or hypotension
• Transient rises in intraocular, intracranial and intragastric pressure
• Excessive salivation, rash

Serious / Life-Threatening

Overdose & Toxicity Management

• Signs: paralysis longer than needed: weakness, low tidal volume, apnea.
• Management: keep the airway, ventilate and keep the patient sedated until spontaneous recovery.
• No antidote: sugammadex does nothing here. Neostigmine prolongs a phase I block. Reserve it for a phase II block, confirmed by train-of-four fade after at least 20 min of plateaued spontaneous recovery. Give it with an anticholinergic, then observe for at least 1 hr (label).

Clinically Significant Interactions

IV Compatibility

• Diluents: D5W or NS for infusion (1–2 mg/mL).
• Incompatible: alkaline solutions with pH above 8.5, such as barbiturates (e.g., methohexital). Flush between drugs.
• Check your institution's compatibility resource.

• Pediatrics: the boxed warning covers hyperkalemic rhabdomyolysis and arrest in undiagnosed myopathy. Emergency airway use only. Ask about developmental delay and motor milestones. Bradycardia is more common and more severe than in adults. The Pediatric Dosing table has the numbers.
• Neonates: the pediatric label runs from neonates to adolescents, for emergency airway use only. Per-kg needs climb. The label sets the adult 0.6 mg/kg against 2–3 mg/kg in neonates and infants up to 6 months, and 1–2 mg/kg in infants up to 2 years. The labeled 2 mg/kg emergency dose names infants and small children. It does not name neonates. Follow neonatal protocol.
• Pregnancy: decades of use have not shown a risk of major birth defects, miscarriage or adverse outcomes. It is commonly used for cesarean delivery. Plasma cholinesterase drops about 24% in pregnancy and for several days postpartum, so apnea may last longer. It crosses the placenta along the concentration gradient. Repeated high doses can cause neonatal apnea and flaccidity. Do not delay an emergency airway.
• Lactation: there are no data on whether it passes into milk or affects the infant. Weigh benefit against risk (label).
• Older Adults: no response differences have been identified. For elective use, start at the low end (label).
• Renal Impairment: about 10% leaves the body unchanged. Severe kidney disease can lower plasma cholinesterase and lengthen the block. Check K⁺ when you can. Avoid it if K⁺ is elevated. Renal failure with a normal K⁺ is not a contraindication.
• Hepatic Impairment: severe liver disease lowers plasma cholinesterase. Expect long paralysis, and be ready to ventilate.
• Obesity / Dosing Weight: dose on actual (total) body weight. A 2021 review found the evidence favors actual weight for succinylcholine. Nondepolarizers are different and use ideal or adjusted weight.
• Pseudocholinesterase Deficiency: inherited BCHE variants reduce or abolish enzyme activity. Homozygous atypical patients, about 1 in 2,500, are extremely sensitive. They can have prolonged apnea and paralysis. Ventilate and sedate. Refer the patient and family for testing.

• Scope: Paramedic and critical-care transport RSI, in the ED and ICU. It varies by state and agency protocol.
• Storage & Stability: keep it refrigerated at 2–8 °C (36–46 °F). Once out of the fridge, a multiple-dose vial stays stable up to 14 days (Hospira label). The 100 mg/5 mL prefilled syringe (OneSource label) is stable 60 days at room temperature. Other prefilled syringes differ, so follow each product's label and date the syringe when you take it out. Keep drug kits away from vehicle heat.
• Carried Concentration: 20 mg/mL is the US strength for vials and prefilled syringes. Keep the paralytic apart in the RSI kit, with its warning cap on, so nobody grabs it by mistake for another drug.
• Before Pushing: run the hyperkalemia and MH screen; preoxygenate; have bag-mask, supraglottic airway and surgical airway ready; draw up post-intubation sedation and analgesia.
• After Intubation: the paralysis wears off in minutes. If a long-acting paralytic follows, sedation and analgesia must run continuously for transport.
• Handoff Essentials: time and dose (mg and mg/kg), any second dose or atropine, later paralytic and time, rhythm changes, EtCO₂ and temperature trend.

Mechanism of Action

• Nicotinic acetylcholine receptor agonist: two acetylcholine molecules joined. It keeps the motor end plate depolarized: fasciculations come first, then flaccid paralysis while the drug stays at the receptor.
• Order of paralysis: facial levator muscles go first, then the glottis, then the intercostals and diaphragm.
• Muscarinic and ganglionic stimulation: bradycardia (especially in children or after a second dose) or tachycardia.
• Potassium efflux through activated receptors: K⁺ rises, and the rise is massive in up-regulated receptor states (burns, denervation, immobility).
• No effect on consciousness or pain: always give an induction agent.

Pharmacokinetics

• Half-life: very short. Plasma levels drop below detection within 2.5 min of a 1–2 mg/kg IV bolus.
• Metabolism: plasma cholinesterase (butyrylcholinesterase, pseudocholinesterase) breaks it down to succinylmonocholine, which has clinically insignificant activity. That then becomes succinic acid and choline.
• Elimination: about 10% leaves the body unchanged in urine.

Generic Name

Succinylcholine chloride (suxamethonium chloride outside the US)

Brand Names

Anectine, Quelicin (US); generics, including prefilled syringes

Pharmacologic Class

Depolarizing neuromuscular blocker (dicholine ester of succinic acid)

Therapeutic Class

Ultra-short-acting skeletal muscle paralytic for intubation and anesthesia

Controlled Substance

Not controlled

ISMP High-Alert

Yes: ISMP high-alert medication (neuromuscular blocking agents)

Look-Alike / Sound-Alike

No specific pair commonly reported; the main error is selecting any paralytic in place of another drug (FDA label warning)