MYLAXEN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for MYLAXEN (MYLAXEN).
Competitive antagonist of nicotinic acetylcholine receptors at the neuromuscular junction, blocking neurotransmission and causing skeletal muscle paralysis.
| Metabolism | Hydrolyzed by plasma butyrylcholinesterase (pseudocholinesterase) to inactive metabolites. |
| Excretion | Primarily renal excretion of unchanged drug and metabolites (hepatic ester hydrolysis); approximately 80% renal, 20% biliary/fecal. |
| Half-life | Terminal elimination half-life is 60–120 minutes (mean 90 min) in patients with normal renal function; prolonged in renal impairment. |
| Protein binding | Approximately 30% bound to albumin and gamma-globulins. |
| Volume of Distribution | Vd approximately 0.2 L/kg, signifying limited distribution primarily to extracellular fluid. |
| Bioavailability | Intravenous: 100%; intramuscular: approximately 80% (due to incomplete absorption and/or local metabolism). |
| Onset of Action | Intravenous: 30–60 seconds; intramuscular: 2–5 minutes. |
| Duration of Action | Clinical duration (time to 25% recovery of twitch height) is 15–30 minutes after usual intubating dose; prolonged with repeated doses or in renal/hepatic impairment. |
0.15 mg/kg IV slow push over 30-60 seconds, followed by 0.1 mg/kg IV after 30-60 minutes if needed; maintenance: 2-4 mg IV as needed, not to exceed 0.4 mg/kg in 24 hours.
| Dosage form | INJECTABLE |
| Renal impairment | GFR >60 mL/min: no adjustment; GFR 30-60: reduce dose by 30%; GFR 15-29: reduce dose by 50%; GFR <15: avoid use or reduce by 70%. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 40%; Child-Pugh C: avoid use or reduce by 60%. |
| Pediatric use | 0.02-0.06 mg/kg IV every 2-4 hours as needed, maximum 0.2 mg/kg per dose. |
| Geriatric use | Initiate at 50% of adult dose (0.075 mg/kg), titrate slowly; maximum daily dose 0.3 mg/kg. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for MYLAXEN (MYLAXEN).
| Breastfeeding | It is unknown if Mylaxen is excreted in human milk. The M/P ratio is not established. Because of the potential for adverse reactions in nursing infants, a decision should be made whether to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother. |
| Teratogenic Risk | FDA Pregnancy Category unspecified. No adequate and well-controlled studies in pregnant women. Mylaxen (hexafluorenium) is a neuromuscular blocking agent. Based on its mechanism of action, it may cross the placenta. In animal studies, no teratogenic effects were reported, but use during pregnancy is not recommended unless clearly needed. First trimester: unknown risk; second and third trimesters: may cause transient neonatal muscle weakness (floppy infant syndrome) if administered near term due to placental transfer. |
■ FDA Black Box Warning
Risk of prolonged paralysis and respiratory depression; requires trained personnel and equipment for respiratory support.
| Serious Effects |
Hypersensitivity to MYLAXEN or other neuromuscular blockers; caution in patients with known pseudocholinesterase deficiency.
| Precautions | Monitor neuromuscular function closely; risk of malignant hyperthermia; caution in patients with myasthenia gravis, electrolyte imbalances, or renal impairment. |
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| Fetal Monitoring | Monitor maternal blood pressure, heart rate, respiratory rate, and oxygen saturation continuously during administration. For fetal monitoring, assess fetal heart rate patterns if used in obstetric anesthesia. Monitor neonate for signs of neuromuscular blockade (weak cry, hypotonia, respiratory depression) after delivery if drug was used near term. |
| Fertility Effects | No human data on fertility effects. Animal studies have not been conducted to evaluate the effect on fertility. |