TUBOCURARINE CHLORIDE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for TUBOCURARINE CHLORIDE (TUBOCURARINE CHLORIDE).
Competitive antagonist at nicotinic acetylcholine receptors (nAChRs) at the neuromuscular junction, blocking ACh binding and preventing depolarization, resulting in skeletal muscle paralysis.
| Metabolism | Minimally metabolized; small amount may be hydrolyzed by liver or plasma esterases; approximately 30-50% excreted unchanged in urine. |
| Excretion | Primarily renal excretion (approximately 70-80% unchanged in urine via glomerular filtration). A minor fraction (10-20%) is excreted in bile into feces. Less than 1% is metabolized (deacetylation to less active desmethyl derivatives). |
| Half-life | Terminal elimination half-life: 1.3–2.9 hours in adults with normal renal function. In renal failure, half-life is prolonged (up to 6–10 hours). Clinically, this leads to prolonged neuromuscular blockade in patients with renal impairment. |
| Protein binding | Approximately 40–50% bound to plasma proteins (albumin and gamma globulins). |
| Volume of Distribution | 0.3–0.6 L/kg (central compartment distribution). This represents the initial volume into which the drug distributes; reflects limited extravascular distribution due to high polarity and poor lipid solubility. |
| Bioavailability | Not applicable orally (negligible due to poor absorption and rapid degradation). Intramuscular bioavailability is unreliable with high variability; intravenous is 100%. |
| Onset of Action | Intravenous: 2–5 minutes (dose-dependent; 0.5 mg/kg yields paralysis within 3–4 minutes). Intramuscular: 10–25 minutes (unreliable; rarely used). |
| Duration of Action | Intravenous: 20–45 minutes for single dose (2× ED95 dose); recovery time to 25% of baseline twitch height is 30–60 minutes. Duration is dose-dependent and prolonged in renal impairment, hepatic dysfunction, or hypothermia. |
0.1-0.2 mg/kg intravenous bolus for initial intubation; maintenance: 0.05-0.1 mg/kg every 20-40 minutes as needed for neuromuscular blockade.
| Dosage form | INJECTABLE |
| Renal impairment | For GFR 10-50 mL/min: reduce dose by 50%; for GFR <10 mL/min: avoid use or use with extreme caution, consider alternative. |
| Liver impairment | Child-Pugh Class A: no adjustment; Class B: reduce dose by 50%; Class C: avoid use. |
| Pediatric use | Infants: 0.15-0.2 mg/kg IV; Children: 0.1-0.2 mg/kg IV; maintenance: 0.05-0.1 mg/kg every 20-45 minutes as needed. |
| Geriatric use | Reduce initial dose by 50% due to decreased clearance and increased sensitivity; monitor recovery of neuromuscular function closely. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for TUBOCURARINE CHLORIDE (TUBOCURARINE CHLORIDE).
| Breastfeeding | It is unknown whether tubocurarine is excreted in human milk. Due to low oral bioavailability and short half-life, systemic exposure in the breastfed infant is likely low. Caution should be exercised, especially in neonates. M/P ratio not available. |
| Teratogenic Risk | Tubocurarine chloride is a non-depolarizing neuromuscular blocking agent. Limited data on human pregnancy. Animal studies indicate no evidence of teratogenicity at clinically relevant doses. In first trimester, risk cannot be excluded; use only if clearly needed. Second and third trimesters: uterine relaxation may occur; potential for fetal hypotonia if used near delivery. Avoid use in pregnancy unless essential. |
■ FDA Black Box Warning
Respiratory depression and apnea require immediate availability of assisted or controlled ventilation; use only by clinicians experienced in endotracheal intubation and respiratory management.
| Serious Effects |
["Hypersensitivity to tubocurarine or its components","Severe anaphylactic reactions history with nondepolarizing muscle relaxants"]
| Precautions | ["Risk of residual neuromuscular blockade requiring reversal agent (neostigmine)","Hypotension and bronchospasm due to histamine release","Malignant hyperthermia (rare)","Potentiated by volatile anesthetics, aminoglycosides, and other nondepolarizing muscle relaxants","Use with caution in patients with myasthenia gravis, electrolyte disorders, and respiratory or hepatic impairment"] |
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| Fetal Monitoring | Monitor maternal vital signs, oxygen saturation, and adequacy of ventilation. Use nerve stimulator to assess degree of neuromuscular blockade. Continuous fetal heart rate monitoring if used during cesarean section to detect fetal distress. Monitor for prolonged neuromuscular blockade in the neonate if used near delivery. |
| Fertility Effects | No adequate studies on human fertility. Animal studies have not shown impairment of fertility. Theoretical risk from prolonged ICU use but not established. |