SYNCURINE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SYNCURINE (SYNCURINE).
Competitive antagonist of nicotinic acetylcholine receptors at the neuromuscular junction, blocking neurotransmission and causing skeletal muscle paralysis.
| Metabolism | Primarily hydrolyzed by plasma pseudocholinesterase (butyrylcholinesterase); a small fraction may be metabolized in the liver. |
| Excretion | Primarily renal excretion (50-70% unchanged drug), with biliary/fecal elimination (10-20%) |
| Half-life | Terminal half-life: 2-5 hours (prolonged with renal impairment; up to 10 hours in severe impairment) |
| Protein binding | ~50% bound to plasma proteins (primarily albumin and globulins) |
| Volume of Distribution | Vd: 0.05-0.1 L/kg (confined to extracellular fluid; minimal tissue distribution) |
| Bioavailability | IM: 100% (complete absorption) |
| Onset of Action | IV: 1-2 minutes (neuromuscular blockade); IM: 2-4 minutes |
| Duration of Action | IV: 10-30 minutes (dose-dependent; prolonged in renal/hepatic impairment); IM: 15-30 minutes |
0.1-0.2 mg/kg IV bolus for paralysis, repeat 0.05-0.1 mg/kg as needed; maintenance infusion 0.5-1.5 mcg/kg/min IV.
| Dosage form | INJECTABLE |
| Renal impairment | No specific dose adjustment defined; use with caution in severe renal impairment (CrCl <30 mL/min) due to potential prolonged effect. |
| Liver impairment | No specific dose adjustment for Child-Pugh A or B; for Child-Pugh C, consider dose reduction of 50% and monitor duration of effect. |
| Pediatric use | Children: 0.15-0.2 mg/kg IV bolus; maintenance infusion 0.5-1 mcg/kg/min. Infants: 0.1 mg/kg IV bolus; infusion 0.4-0.8 mcg/kg/min. |
| Geriatric use | Elderly patients may have increased sensitivity; consider dose reduction by 25-50% and monitor for prolonged neuromuscular blockade. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for SYNCURINE (SYNCURINE).
| Breastfeeding | Excretion into human milk unknown. M/P ratio not available. Consider benefits of breastfeeding vs potential for adverse effects in infant (e.g., neuromuscular blockade). |
| Teratogenic Risk | No adequate studies in pregnant women. Animal studies not available. Risk cannot be ruled out; first trimester: theoretical risk of skeletal muscle weakness if depolarizing neuromuscular blocker crosses placenta; second and third trimesters: may cause transient neonatal muscle weakness if administered near delivery. |
■ FDA Black Box Warning
Should be administered only by individuals trained in the use of neuromuscular blocking agents and the management of respiratory depression. Resuscitative equipment and personnel must be immediately available. Use with caution in patients with myasthenia gravis or electrolyte abnormalities due to risk of prolonged paralysis.
| Serious Effects |
Known hypersensitivity to succinylcholine; patients with a history of malignant hyperthermia; patients with recent burns, trauma, or neurological injury due to risk of hyperkalemia; patients with skeletal myopathies associated with elevated serum creatine kinase; patients with acute narrow-angle glaucoma.
| Precautions | Risk of prolonged neuromuscular blockade in patients with pseudocholinesterase deficiency; potential for histamine release leading to hypotension and bronchospasm; may cause malignant hyperthermia in susceptible individuals; use with caution in patients with severe hepatic or renal impairment. |
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| Fetal Monitoring |
| Monitor maternal neuromuscular function (train-of-four) and fetal heart rate during prolonged use. Monitor neonatal respiratory function and muscle tone after delivery if used near term. |
| Fertility Effects | No data on effects on human fertility. Animal reproductive studies not conducted. |