Neuromuscular Relaxants

Question 1

Succinylcholine

Answer 1

Indications: Tracheal intubation or ECT
MoA: Depolarization blockade of muscle nicotinic receptors
Adverse effects: Not analgesic, apnea, muscle pain, intraocular pressure/intragastic pressure, arrhythmia, hypertension, bradycardia, hyperkalemia
Contraindications: Family history of malignant hyperthermia, burns (early), major soft tissue injury (delayed), skeletal muscle myopathies
Misc:

Question 2

Pancuronium

Answer 2

Indications: Adjuvant in surgical anesthesia, abdominal wall relaxation and orthopedic procedures
MoA: Non-depolarizing blockade of muscle nicotinic receptors
Adverse effects: Not analgesic, apnea, muscarinic blockade (increased HR and CO)
Contraindications:
Misc: Duration of action 30-60 min

Question 3

D-tubocurarine

Answer 3

Indications: Prototype, only used in lethal injection
MoA: Non-depolarizing blockade of muscle nicotinic receptors
Adverse effects: Not analgesic, apnea
Contraindications:
Misc: Duration of action 60 min

Question 4

Rocuronium

Answer 4

Indications: Intubation, muscle relaxation during surgery or ventilation
MoA: Non-depolarizing blockade of muscle nicotinic receptors
Adverse effects: Not analgesic, apnea, muscarinic blockade (increased HR and CO)
Contraindications:
Misc: Duration of action 25 min

Question 5

Mivacurium

Answer 5

Indications: Intubation, muscle relaxation during surgery or ventilation in patients with renal failure
MoA: Non-depolarizing blockade of muscle nicotinic receptors
Adverse effects: Not analgesic, apnea, histamine release
Contraindications: Inhalation anesthetics, antibiotics
Misc: Duration of action 15-20 minutes

Question 6

Vecuronium

Answer 6

Indications: Adjuvant in surgical anesthesia, abdominal wall relaxation and orthopedic procedures
MoA: Non-depolarizing blockade of muscle nicotinic receptors
Adverse effects: Not analgesic, apnea
Contraindications: Duration of action 30-45 min
Misc:

Question 7

Baclofen

Answer 7

Indications: Muscle spasticity associate with MS or spinal cord injury
MoA: GABA agonist. Inhibits NT release from skeletal muscle sensory afferent
Adverse effects: Drowsiness, AMS
Contraindications:
Misc: Reduces Ca influx at 1a afferent nerve terminal. If given intrathecally (in the spinal cord), reduces drowsiness

Question 8

Diazepam

Answer 8

Indications: Muscle spasm d/t local injury (inflammation), muscle spasticity d/t loss of descending inhibitory input e.g. cerebral palsy
MoA: Benzodiazepine receptor agonist
Adverse effects: Drowsiness, sedation
Contraindications: acute narrow-angle glaucoma, untreated open-angle glaucoma
Misc: Positive allosteric modulators of GABAa receptors, increase GABA-mediated Cl influx

Question 9

Tizanidine

Answer 9

Indications: Muscle spasticity d/t spinal cord injury or MS
MoA: Centrally acting a2 agonist
Adverse effects: Drowsiness, hypotension
Contraindications:
Misc: Pre and post synaptic inhibition in spinal cord

Question 10

Dantrolene

Answer 10

Indications: Muscle spasm, malignant hyperthermia
MoA: Uncouple excitation-contraction of skeletal muscle (block ryanodine receptor)
Adverse effects: Muscle weakness, sedation, hepatitis
Contraindications:
Misc: Prevents Ca efflux from SR into the cell