METOCURINE IODIDE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for METOCURINE IODIDE (METOCURINE IODIDE).
Competitive nicotinic acetylcholine receptor antagonist at the neuromuscular junction, blocking acetylcholine binding and preventing muscle contraction.
| Metabolism | Primarily hepatic metabolism via unclear pathways; some renal excretion of unchanged drug. |
| Excretion | Renal: 85-90% unchanged; biliary/fecal: <5%. |
| Half-life | Terminal elimination half-life: 3-5 hours in patients with normal renal function. Prolonged in renal impairment. |
| Protein binding | ~30% bound to albumin. |
| Volume of Distribution | Vd: 0.3-0.5 L/kg; approximates extracellular fluid volume. |
| Bioavailability | IV only; negligible oral bioavailability (<5% due to poor absorption and first-pass metabolism). |
| Onset of Action | IV: 1-2 minutes for intubating doses (0.2-0.3 mg/kg); onset fastest with adequate circulation. |
| Duration of Action | IV: Clinical duration (time to 25% recovery of twitch) 60-90 minutes after intubating dose; prolonged in renal failure. |
Initial dose 0.2 mg/kg IV; maintenance doses of 0.1-0.15 mg/kg IV as needed for neuromuscular blockade.
| Dosage form | Injectable |
| Renal impairment | No specific GFR-based dose adjustments available; use with caution in renal impairment due to potential prolonged effect. |
| Liver impairment | No specific Child-Pugh based adjustments; caution in severe hepatic impairment as metabolism may be reduced. |
| Pediatric use | Neonates and infants: 0.15-0.2 mg/kg IV; children: 0.2-0.3 mg/kg IV. Doses repeated as needed. |
| Geriatric use | Reduce initial dose by 50% in elderly due to increased sensitivity and prolonged duration; titrate carefully. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for METOCURINE IODIDE (METOCURINE IODIDE).
| Breastfeeding | Metocurine iodide is a quaternary ammonium compound with low lipid solubility and high molecular weight, likely resulting in minimal transfer into breast milk. No specific M/P ratio is available. Systemic absorption by the infant via oral ingestion is negligible due to poor gastrointestinal absorption of quaternary amines. Therefore, breastfeeding is considered safe following maternal administration. The American Academy of Pediatrics classifies it as compatible with breastfeeding. |
| Teratogenic Risk | Metocurine iodide is a nondepolarizing neuromuscular blocking agent. Available data from animal studies and human case reports are insufficient to determine a definitive teratogenic risk. No specific malformation pattern has been associated with first-trimester exposure. Fetal effects from maternal administration during pregnancy are mainly related to maternal hypotension and hypoxemia, which may indirectly affect fetal perfusion. Prolonged use near term may theoretically cause transient neonatal myasthenia gravis-like syndrome (weakness, hypotonia, respiratory depression) due to placental transfer. However, typical obstetric use is limited to short duration during cesarean delivery. Risk cannot be excluded; use only if clearly indicated. |
■ FDA Black Box Warning
Should be administered by experienced clinicians familiar with neuromuscular blocking agents; appropriate resuscitation equipment must be immediately available due to risk of prolonged paralysis and respiratory depression.
| Serious Effects |
["Hypersensitivity to metocurine or any component","Myasthenia gravis (relative, may require reduced dose)","Severe hepatic or renal impairment"]
| Precautions | ["Risk of prolonged neuromuscular blockade in patients with hepatic or renal impairment","May cause histamine release leading to hypotension and bronchospasm","Use with caution in patients with cardiovascular disease, myasthenia gravis, or electrolyte imbalances","Residual paralysis should be monitored and reversed appropriately"] |
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| Fetal Monitoring | Continuous maternal monitoring of vital signs (heart rate, blood pressure, oxygen saturation) and neuromuscular function (using train-of-four peripheral nerve stimulation) is required during administration. Fetal heart rate monitoring should be performed when feasible, particularly during cesarean delivery. Assess for signs of maternal hypotension and promptly treat with fluid resuscitation and vasopressors as needed to maintain uterine perfusion. After delivery, monitor the neonate for signs of neuromuscular blockade (weak cry, poor suck, hypotonia, respiratory distress) if large doses were used near term. |
| Fertility Effects | No human data are available regarding effects on fertility. Animal studies have not been conducted to evaluate reproductive toxicity. There is no known mechanism by which acute administration of a neuromuscular blocker would impair fertility. Based on its pharmacodynamic profile, metocurine iodide is not expected to have any significant impact on male or female fertility. |