succinylcholine (Anectine, Flo-Pack, Quelicin, Sucostrin, Myorelaxin)

Introduction

Tradenames: Anectine, Flo-Pack, Quelicin, Sucostrin.

Indications

• skeletal muscle relaxation during
  • short surgical procedures under general anesthesia
  • endoscopic examinations
  • orthopedic manipulation
  • electroshock therapy
  • endotracheal intubation
• must ALWAYS be used with sedatives, i.e.lorazepam or anesthetic & an analgesic as needed

Contraindications

• malignant hyperthermia
• myopathies associated with elevated serum creatinine
• narrow-angle glaucoma
• penetrating eye injuries
• disorders of plasma pseudocholinesterase
• children & adolescent except for emergency endotracheal intubation

Caution:

• hyperkalemia
• paraplegia
• extensive or severe burns
• dystrophic neuromuscular disease

pregnancy category = c

safety in lactation = ?

Dosage

• 0.6.0-1.5 mg/kg up to 150 mg IV bolus over 10-30 seconds
• repeat as necessary
• infusion: 0.5-10 mg/min
• intermittent dosing:
  • 0.3-1.1 mg/kg initial dose
  • followed by 0.04-0.07 mg/kg as necessary
• pediatrics: 2 mg/kg IV preceded by atropine 0.02 mg/kg
• pretreatment with atropine may reduce the incidence of bradycardia

Injection: 20 mg/mL (10 mL).

Powder for injection: 500 mg. 1 g.

Pharmacokinetics

• rapid onset of action (30-60 seconds)
• duration of action:
  • 30 minutes; 2-5 minutes
  • determined by rate of diffusion away from motor end plate
• metabolized rapidly by pseudocholinesterase to a less active metabolite which produces a non-depolarizing neuromuscular block; this metabolite may accumulate causing prolonged apnea
• 10% excreted unchanged in the urine

elimination via plasma

Adverse effects

• common (> 10%)
  • postoperative stiffness, increased intraocular pressure
• less common (1-10%)
  • excessive salivation, tachycardia, bradycardia
• uncommon (< 1%)
  • rash, itching, malignant hyperthermia, hypertension, erythema, circulatory collapse, bronchospasm
• other
  • tachyphylaxis
  • muscle fasciculations*
  • hypotension
  • increased intragastric pressure
  • increased side effects noted when K+ levels are decreased or elevated
  • prolonged post-surgical apnea associated with mutant alleles of BuChE gene (BCHE gene mutation)

* initial muscle fasciculations may result in post-operative pain

Antidote: neostigmine, give with atropine in glycopyrrolate.

Drug interactions

• aminoglycosides, tetracyclines, clindamycin: in combination prolong & increase neuromuscular blockade
• corticosteroids: in combination prolong muscle weakness
• K+ depleting agents (thiazides, loop diuretics, amphotericin B corticosteroids): increase & prolong neuromuscular paralysis
• cholinesterase inhibitors: reverse neuromuscular blockade
• organophosphates: reduce plasma levels of pseudocholinesterase which can can prolonged apnea
• malignant hyperthermia when used with halothane

• drug interaction(s) of lithium carbonate with neuromuscular blockers

Laboratory

• BCHE gene mutation
• succinylcholine in serum/plasma
• succinylcholine in urine

Mechanism of action

• depolarizing neuromuscular blocking agent
• skeletal muscle relaxation is produced by decreasing the response to acetylcholine at the myoneural junction
• blocks access of acetylcholine to the motor end-plate

More general terms

• neuromuscular blocker (paralyzing agent)

Additional terms

• atropine (Atropair, Atropine-Care)
• glycopyrrolate (Robinul, Cuvposa, Qbrexza)
• neostigmine (Prostigmin)

Database

• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=5314
• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=22475
• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=68325
• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=66129