Neuromuscular Blockers

Question 1

Succinylcholine (Anectine)

Onset: 30-60 seconds (IV)
Peak effects: 1-3 minutes
Duration: 2-3 minutes (IV)
Half-life: 5-10 minutes

MOA: a short-acting, depolarizing skeletal muscle relaxant. Like acetylcholine, it combines with cholinergic receptors in the motor nerves to cause depolarization. Neuromuscular transmission is then inhibited.

Answer 1

Class: depolarizing neuromuscular blocker

Action: short-acting, depolarizing skeletal muscle relaxant used to facilitate intubation

Indications: temporary paralysis when intubation is indicated and muscle tone or seizure activity prevents it

Contraindications: known hypersensitivity, penetrating eye injuries, Hx of narrow-angle glaucoma

Side effects: wheezing, respiratory depression, apnea, aspiration, arrhythmias, bradycardia, sinus arrest, HTN, hypotension, hyperkalemia, increased intraocular pressure, increased ICP, malignant hyperthermia

Interactions: meds that can enhance the neuromuscular blocking action: lidocaine, procainamide, beta-blockers, magnesium sulfate, and other neuromuscular blockers

Route: IV

Adult dose: 1-1.5 mg/kg (40-100 mg in adult)

Peds dose: 1 mg/kg

Question 2

Vecuronium (Norcuron)

Onset: less than 1 minute
Peak effects: 3-5 minutes
Duration: 25-40 minutes
Half-life: 30-80 minutes

MOA: Vecuronium competes with acetylcholine for cholinergic receptor sites on the postjuctional membrane. This competition results in paralysis of muscle fibers served by the occupied neuromuscular junction.

Answer 2

Class: Nondepolarizing neuromuscular blocker

Action: used to provide muscle relaxation to facilitate endotracheal intubation

Indications: used to achieve temporary paralysis when endotracheal intubation is indicated and muscle tone or seizure activity prevents it

Contraindications: known hypersensitivity

Side effects: wheezing, respiratory depression, apnea, aspiration, arrhythmias, bradycardia, sinus arrest, HTN

Interactions: certain meds can enhance the neuromuscular blocking action of vecuronium: lidocaine, procainamide, beta-blockers, magnesium sulfate, and other neuromuscular blockers

Route: IV

Adult dose: 0.08-0.1 mg/kg

Peds dose: 0.1 mg/kg

Question 3

Rocuronium Bromide (Zemuron)

Onset: 30-60 seconds
Peak effects: 1-3 minutes
Duration: 30-60 minutes
Half-life: 14-18 minutes

MOA: Rocuronium acts by binding competitively to cholinergic receptors at the motor end plate to antagonize the action of acetylcholine, an effect that is reversible in the presence of acetylcholinesterase inhibitors, such as neostigmine and edrophonium

Answer 3

Class: Nondepolarizing neuromuscular blocker

Action: a nondepolarizing neuromuscular blocking agent with a rapid to intermediate onset, and intermediate duration of action

Indications: indicated as an adjunct to general anesthesia to facilitate both RSI and routine endotracheal intubation, and to provide skeletal muscle relaxation during surgery or mechanical ventilation

Contraindications: known hypersensitivity

Precautions: Rocuronium is associated with a slight elevation in BP and heart rate; tachycardia may occur in children. Underlying cardiovascular disease, dehydration or electrolyte abnormalities

Side effects: bronchospasm (rare)

Interactions: intensity and duration of paralysis may be prolonged by pretreatment with succinylcholine general anesthesia (inhalation), lidocaine, quinidine, procainamide, beta-adrenergic blocking agents, potassium-losing diuretics, or magnesium

Route: IV, IV drip

Adult dose: Initial dose RSI- 600 mcg/kg
Maintenance dose- 100-200 mcg/kg continuous infusion

Peds dose: Initial dose- 600 mcg/kg
Maintenance dose- 75-125 mcg/kg continuous infusion