free collaborative open access anaesthesia education

NEOSTIGMINE

CLASS

Anticholinesterase

PRESENTATION

Clear, colourless solution in transparent ampoule.

Formulations

  • 2.5mg in 1ml

INDICATIONS & DOSING

Reversal of non-depolarising neuromuscular blockade

  • Adult; 2.5mg IV, max 5mg
  • Paed; 50mcg/kg IV, max 2.5mg

Prophylaxis of postoperative gastrointestinal atony, urinary retention

  • Adult; 0.25-0.5mg IM/SC, pre/intraoperatively followed by Q4-6h for 2-3 days¬†

PRACTICALITIES

Administration

  • 2.5mg neostigmine is administered in combination with 400mcg glycopyrrolate to offset non-neuromuscular muscarinic effects

Incompatibilities

  • Nil significant

Practice tips

  • Use as a reversal agent should not be attempted until some degree of spontaneous recovery is evident (TOF count >1)
  • The speed of reversal of neuromuscular blockade is mainly determined by the depth of neuromuscular blockade prior to administration
  • Neuromuscular monitoring is recommended to confirm reversal of paralysis due to multitude of other factors that may augment effect of neuromuscular blockers
  • Administration may complicate management of those with myasthenia gravis on cholinergic treatment (variable response, precipitation of cholinergic crisis), consider use of sugammadex instead

PHARMACOKINETICS

Onset

  • IV; ~5-15 minutes

Duration of action

  • 40-60 minutes following bolus dose

Metabolism

Majority hepatic, hydrolysis of ester linkages and metabolism by microsomal enzymes

Elimination

Renally excreted, 50% unchanged, 50% as metabolites of parent molecule

MECHANISM

Reversible inhibition of acetylcholine hydrolysis by competition for attachment to acetylcholinesterase increases nerve terminal acetylcholine concentrations, augmenting neuromuscular transmission

DESIRED CLINICAL EFFECTS

Neuromuscular

  • Reversal of neuromuscular blockade and paralysis

OTHER CLINICAL EFFECTS, ADVERSE EFFECTS & TOXICITIES

Respiratory

  • Increased airway secretions
  • Bronchospasm
  • Respiratory depression/arrest (overdose)

Cardiovascular

  • Bradycardia, reduced cardiac output, hypotension/cardiac arrest
  • Bradyarrhythmia

Neurological

  • Headache, vertigo, restlessness
  • Agitation, slurred speech, ataxia seizures, drowsiness/coma (overdose)

Neuromuscular

  • Fasciculations, cramps
  • Generalised weakness, paralysis (overdose)

Renal & electrolytes

  • Urinary incontinence

Gastrointestinal

  • Nausea/vomiting, abdominal cramps, diarrhoea
  • Faecal incontinence

Other

  • Sweating, salivation
  • Miosis,¬†diplopia, nystagmus, lacrimation
  • Precipitation of cholinergic crisis

Antidote

  • Atropine, glycopyrrolate

CONSIDERATIONS

Precautions

  • Bronchospastic disease
  • Mechanical intestinal or urinary tract obstruction, recent gastrointestinal surgery, recent bladder surgery
  • Cardiovascular compromise; hypotension/shock states, coronary ischaemia, bradycardia/conduction defects

Obstetric 

Category B2; may increase uterine irritability and induce premature labour in late gestation

Drug interactions

  • Suxamethonium; prolongation of phase 1 block
  • Anaesthetics agents, sodium channel blockers, lithium, calcium channel blockers, aminoglycoside antibiotics; diminished efficacy

REFERENCES

Drug information has been compiled from multiple sources including

  • Drugs in Anaesthesia and Intensive Care (Scarth & Smith)
  • Micromedex (IBM)
  • BJA Education (Oxford Academic)
  • Pharmacology for Anaesthesia and Intensive Care (Cambridge)
  • Australian Prescriber (NPS MedicineWise)
  • Clinical experience of authors

Leave a Reply

Close Menu