SUCOSTRIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SUCOSTRIN (SUCOSTRIN).
Succinylcholine is a depolarizing neuromuscular blocker that binds to and activates nicotinic acetylcholine receptors at the neuromuscular junction, causing initial muscle fasciculations followed by prolonged depolarization and receptor desensitization, resulting in neuromuscular blockade.
| Metabolism | Rapidly hydrolyzed by plasma butyrylcholinesterase (pseudocholinesterase) into succinylmonocholine and choline. |
| Excretion | Primarily renal excretion of unchanged drug and metabolites (succinylmonocholine); minimal biliary/fecal elimination (<2%). Approximately 10-20% excreted unchanged in urine, with the remainder as succinylmonocholine. |
| Half-life | Terminal elimination half-life is approximately 2-4 minutes for succinylcholine (rapid hydrolysis by plasma pseudocholinesterase). In patients with atypical pseudocholinesterase or deficiency, half-life may be prolonged to 20-60 minutes, leading to prolonged paralysis. |
| Protein binding | Minimal protein binding (<5%) due to rapid hydrolysis; not significantly bound to albumin or other plasma proteins. |
| Volume of Distribution | 0.2-0.4 L/kg (approximately 15-30 L in adults). Low Vd indicates confinement to extracellular fluid and rapid distribution to neuromuscular junction. |
| Bioavailability | Intravenous: 100%. Intramuscular: approximately 50-60% (due to hydrolysis at injection site and first-pass metabolism by tissue esterases). |
| Onset of Action | Intravenous: 30-60 seconds. Intramuscular: 2-3 minutes. |
| Duration of Action | Intravenous: 4-6 minutes for single dose (depolarizing block). Clinical effect terminated by rapid hydrolysis; prolonged with repeated doses or infusion due to phase II block (desensitization). |
IV: 0.3-1.1 mg/kg initially, then maintenance of 0.04-0.07 mg/kg as needed or continuous infusion of 2.5-4.3 mg/min.
| Dosage form | INJECTABLE |
| Renal impairment | No specific dose adjustment recommended for GFR <10 mL/min; use with caution due to prolonged duration. |
| Liver impairment | No specific Child-Pugh based adjustment; use with caution in severe hepatic impairment. |
| Pediatric use | IV: 1-2 mg/kg initially, then 0.3-0.6 mg/kg as needed or continuous infusion of 2.5-4 mg/min. |
| Geriatric use | Use lower initial doses (0.3-0.6 mg/kg); increased sensitivity and prolonged recovery possible. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for SUCOSTRIN (SUCOSTRIN).
| Breastfeeding | Succinylcholine is excreted into breast milk in minimal amounts; its rapid hydrolysis limits infant exposure. The milk-to-plasma ratio is unknown. The American Academy of Pediatrics considers it compatible with breastfeeding. However, due to potential infant effects (e.g., muscle weakness), caution is advised. |
| Teratogenic Risk | Succinylcholine (suxamethonium) is a depolarizing neuromuscular blocker. It does not cross the placenta in clinically significant amounts due to its rapid hydrolysis by plasma pseudocholinesterase. Studies in pregnant women have not shown an increased risk of fetal malformations. However, prolonged use in pregnancy may lead to fetal paralysis if the drug crosses in high doses, but this is rare. Use only when clearly needed. |
■ FDA Black Box Warning
Risk of ventricular dysrhythmias, cardiac arrest, and death due to hyperkalemia in patients with undiagnosed skeletal muscle myopathies, especially in children. Use caution and consider alternative agents in patients with known or suspected susceptibility to malignant hyperthermia or myopathies.
| Serious Effects |
["Known hypersensitivity to succinylcholine","History of malignant hyperthermia","Personal or family history of skeletal muscle myopathies (e.g., Duchenne muscular dystrophy)","Acute phase of major burns or massive tissue trauma (risk of hyperkalemia)","Patients with known low plasma pseudocholinesterase activity or genetic deficiency","Narrow-angle glaucoma (relative contraindication)"]
| Precautions | ["Risk of hyperkalemia in patients with major burns, trauma, massive tissue necrosis, denervation, or prolonged immobilization","May trigger malignant hyperthermia in susceptible individuals","Increased intraocular, intragastric, and intracranial pressure","Prolonged neuromuscular blockade in patients with genetic variants of butyrylcholinesterase","Risk of bradycardia, especially with repeated doses"] |
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| Fetal Monitoring | Monitor maternal vital signs, oxygen saturation, and neuromuscular function (using a peripheral nerve stimulator to assess depth of paralysis). Fetal monitoring (heart rate, tone) may be considered if prolonged use or high doses are administered. Watch for maternal malignant hyperthermia and prolonged apnea due to pseudocholinesterase deficiency. |
| Fertility Effects | There is no known effect on human fertility. Succinylcholine is a short-acting agent used for anesthesia; no reproductive toxicity has been reported. |