Succinylcholine Chloride
Suxamethonium chloride
Also known as: Anectine · Quelicin · choline chloride succinate · succicurarium chloride · suxamethonii chloridum · suxametonklorid · suxamethonium chloride
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Muscle relaxation | 0.07 mg/kg | IV | Single dose | — | 🌎 NA |
| Muscle relaxation | 0.22 mg/kg | IV | Single dose | — | 🌎 NA |
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Muscle relaxation | 0.06 mg/kg | IV | Single dose | — | 🌎 NA |
| Muscle relaxation | 0.11 mg/kg | IV | Single dose | — | 🌎 NA |
Reptiles
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| To relax an animal to allow intubation | 0.5-1 mg/kg | IM | Single dose | — | 🌎 NA |
- To relax an animal to allow intubation: Especially helpful with turtles and crocodilians.
Horses
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Muscle relaxation | 0.088-0.11 mg/kg | IV, IM | Single dose | — | 🌎 NA |
- Muscle relaxation: See Precautions. ARCI UCGFS Class 2 Drug. 0.088 mg/kg IV may paralyze skeletal muscles without causing respiratory depression, but higher doses cause apnea.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Succinylcholine chloride is an ultrashort-acting, depolarizing skeletal muscle relaxant (paralytic).
Key Clinical Points:
- No Analgesia or Sedation: Succinylcholine provides absolutely no pain relief or unconsciousness. Patients are fully awake and can feel pain but are completely paralyzed. It must always be used with appropriate sedatives, anesthetics, and analgesics.
- Ventilatory Support Required: Because it paralyzes the diaphragm and intercostal muscles, mechanical ventilation is mandatory until the drug wears off.
- Clinical Use: Primarily used for short-term muscle relaxation to facilitate endotracheal intubation (Rapid Sequence Intubation), surgical/diagnostic procedures, or to reduce muscle contractions during convulsions.
- Species Differences: While it has a very short duration in humans and most animals (2-3 minutes), dogs exhibit an idiosyncratic prolonged duration of action (≈ 20 minutes).
- Modern Usage: Its use in veterinary medicine has largely been supplanted by non-depolarizing agents (e.g., atracurium, rocuronium) which have fewer adverse effects and are reversible.
Mechanism of action
Succinylcholine acts as a depolarizing neuromuscular blocker.
- Binding: It acts as a structural analog of acetylcholine (ACh) and binds to nicotinic acetylcholine receptors (nAChRs) at the motor endplate of the neuromuscular junction.
- Depolarization: Unlike ACh, which is instantly degraded by acetylcholinesterase, succinylcholine remains bound, causing prolonged depolarization of the muscle membrane. This initial depolarization manifests clinically as transient muscle twitches (fasciculations).
- Paralysis: Because the membrane cannot repolarize, it becomes unresponsive to subsequent ACh release → flaccid paralysis (Phase I block).
- Metabolism: The blockade persists until succinylcholine diffuses away from the receptor and is rapidly hydrolyzed by plasma pseudocholinesterase (butyrylcholinesterase) in the blood.
Safety & warnings
Contraindications
- Severe liver disease
- Chronic anemias
- Chronic malnourishment
- Glaucoma or penetrating eye injuries
- Predisposition to malignant hyperthermia
- Increased CPK values with resultant myopathies
- Recent use of organophosphate agents
Adverse effects
- Muscle soreness
- Histamine release
- Malignant hyperthermia
- Excessive salivation
- Hyperkalemia
- Rash
- Myoglobinemia
- Myoglobinuria
- Bradycardia
- Tachycardia
- Hypertension
- Hypotension
- Arrhythmias
Precautions
CRITICAL WARNING: Succinylcholine has NO analgesic or anesthetic effects. It must be used with appropriate analgesic, sedative, and anesthetic agents. Mechanical ventilation is required.
- Hyperkalemia Risk: Use with extreme caution in patients with traumatic wounds, burns, preexisting hyperkalemia, or electrolyte imbalances, as fatal arrhythmias or cardiac arrest may occur due to sudden potassium efflux from muscle cells.
- Organ Dysfunction: Use with caution in patients with pulmonary, renal, cardiovascular, metabolic, or hepatic dysfunction.
- Equine Specifics (AAEP Recommendations): Inform owners it is a restraining agent, not an anesthetic. Do not use if the horse has received 'mycin' antibiotics, organophosphates, cholinesterase inhibitors, or procaine within 30 days. Do not use in debilitated/exhausted horses. Withhold food 4-6 hours prior. Be prepared to administer oxygen and artificial respiration. Have a handler prevent the horse from falling forward.
Drug interactions
May increase succinylcholine's effects by causing electrolyte imbalances
Succinylcholine may cause a sudden outflux of potassium from muscle cells, causing arrhythmias in digitalized patients
Potential for increased incidences of bradycardia and sinus arrest
May increase succinylcholine's effects by causing electrolyte imbalances
May increase or prolong neuromuscular blockade
May increase or prolong neuromuscular blockade
May increase or prolong neuromuscular blockade
May increase or prolong neuromuscular blockade
May increase or prolong neuromuscular blockade
May increase or prolong neuromuscular blockade
May increase or prolong neuromuscular blockade (Contraindicated)
Monitoring
- Level of muscle relaxation
- Cardiac rate and rhythm (ECG)
- Respiratory depressant effect (Apnea)
- Oxygenation (Pulse oximetry) and Ventilation (Capnography)
- Body temperature (risk of malignant hyperthermia)
Pharmacokinetics
Half-life
Absorption
IV onset of action is usually within 30-60 seconds. IM onset is generally within 2-3 minutes.
Distribution
Diffuses away from the motor end plate. Crosses the placenta in low concentrations.
Metabolism
Rapidly hydrolyzed by plasma pseudocholinesterases to succinylmonocholine (weak blocking activity) and choline.
Elimination
10% is excreted unchanged in the urine. Succinylmonocholine is partially excreted in the urine and may accumulate in renal impairment.
Overdose
Inadvertent overdoses, or standard doses in patients deficient in pseudocholinesterase, may result in prolonged apnea.
- Treatment: Mechanical ventilation with 100% O2 must be maintained until full spontaneous recovery occurs.
- Phase II Block: Repeated or prolonged high dosages may cause patients to convert from a depolarizing (Phase I) block to a non-depolarizing-like (Phase II) block.
Available products
Formulations
- Injection solution
- Powder for infusion
Human-labeled
- Succinylcholine Chloride Injection: 20 mg/mL in 10 mL vials and 5 mL syringes
- Succinylcholine Chloride Injection, Solution: 100 mg/mL in 5 mL & 10 mL vials
- Succinylcholine Chloride Powder for Infusion: 500 mg & 1 gram in vials
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Commercial injectable solutions should be stored refrigerated (2°-8°C). Multiple dose vials of Anectine are stable up to 2 weeks at room temperature. Powder forms are stable indefinitely unopened at room temperature. Reconstituted powder is stable for 4 weeks at 5°C or 1 week at room temperature, but use within 24 hours is recommended as it contains no preservatives.
Client information
This medication is strictly for use by trained veterinary professionals in a clinical setting.
- Important: This drug is a paralytic. It stops muscles from moving, including the muscles used for breathing, but it does not provide any pain relief or sedation.
- Your pet will be given other medications to ensure they are fully asleep and pain-free before this drug is administered.
- Because it stops breathing muscles, the veterinary team will place a breathing tube and use a machine to breathe for your pet until the drug wears off completely.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.