- used to produce skeletal muscle relaxation/paralysis in uncooperative neonates who are mechanically ventilated
- vecuronium competes with acetylcholine for receptor sites on the postjunctional membrane, thereby interrupting transmission of nerve impulses at the neuromuscular junction
- it is a non-depolarizing agent; this means that muscular paralysis can be reversed if the concentration of acetylcholine is increased, by using an anticholinesterase inhibitor such as neostigmine, edrophonium or pyridostigmine
- prematurity, acidosis, hypothermia and use within the first week are factors that dictate a low dose
- the dose and duration do not, in general, predict the time to recovery; 20 hours in an average time to full recovery - this, however, can be prolonged by prematurity and renal failure
- vecuronium and its metabolites appear to be excreted principally in feces via biliary elimination
- approximately 20-30% of vecuronium is excreted in the urine, principally as unchanged drug
- note that the elimination of pancuronium is quite different; pancuronium is eliminated mainly unchanged by the kidneys, a small amount is excreted in the bile
- local irritation (redness, induration) is relatively infrequent
- cardiovascular effects (tachycardia, increased blood pressure) are minimal and uncommon; note that tachycardia and increased blood pressure are frequently seen with Pancuronium (this occurs via vagal blockade)
- unlike some other neuromuscular blocking agents (eg. atracurium) vecuronium does not cause histamine release
- MECHANICAL VENTILATION USUALLY PRECEDES THE USE OF VECURONIUM. HOWEVER, IT MAY BE USED TO FACILITATE A DIFFICULT INTUBATION.
- once the infant is paralyzed, dramatic changes in the respiratory settings may be necessary
- aminoglycoside antibiotics (eg. gentamicin) potentiate neuromuscular blockage, leading to increased skeletal muscle relaxation
- opiates can cause CNS respiratory depression which can add to the respiratory depressant effects of vecuronium
- monitor baseline electrolyte values since electrolyte imbalance can potentiate neuromuscular effects
- respiration and heart rate should be monitored continuously
- must have constant nursing observation
- give eye care every 30-60 minutes; use methylcellulose 0.5% solution to keep eyes lubricated, apply eye pad covers
- measure accurate intake and output; renal dysfunction may prolong duration of action
- do not store in plastic containers or syringes, although plastic syringes may be used for administration; use only fresh solutions
- blood gases must be done 20-30 minutes after first dose
- observe the infant for return of skeletal muscle activity and consult the physician regarding further drug administration
Reversal of Neuromuscular Blockade
- neuromuscular blockade can be reversed by administering a cholinesterase inhibitor such as neostigmine
DOSE - FOR REVERSAL OF NEUROMUSCULAR BLOCKADE
- give atropine prior to neostigmine, to prevent vagal reaction (bradycardia, bronchospasm, increased salivation)
- neostigmine 0.06 mg/kg slow IV push by physician only
- also give atropine 0.02 mg/kg IV push by physician only
DOSE - FOR VECURONIUM
- dosage must be individualized in each case
- 0.08 to 0.1 mg/kg, IV push, by a physician only
- in the presence of potent inhalational anesthetics, the neuromuscular blocking effect of vecuronium is enhanced, and the initial vecuronium dose may be reduced
- prior administration of succinylcholine may enhance the neuromuscular blocking affect and duration of action of vecuronium
- maintenance doses of 0.01 to 0.015 mg/kg have been given to patients who are receiving inhalational anaesthesia during surgical procedures; since the neuromuscular blocking action of vecuronium is slightly enhanced in the presence of inhalational anaesthetics, infants who are not receiving inhalational anaesthesia may require a higher maintenance dose than listed above
- given IV push by a physician only
- Children 7 weeks to 1 year are moderately more sensitive to vecuronium on a mg/kg basis than adults and take about 1 1/2 times as long to recover. The recovery time (spontaneous recovery of the twitch response from 25% to 75% of the control response) following administration of vecuronium 0.08-0.1mg/kg to adults under balanced or halothane anaesthesia is about 15-25 minutes. Repeated administration of maintenance doses of vecuronium appears to have little, if any, cumulative effect on the rate of recovery from neuromuscular blockade.
Continuous IV Infusion
- an initial dose of 0.08 to 0.1 mg/kg, IV push, by a physician only.
- a continuous IV infusion may be started only after spontaneous recovery from the initial IV dose is evident.
- an initial vecuronium infusion rate of 1 mcg/kg/min is recommended following STEPS 1 and 2 above.
in patients with renal or hepatic impairment or in premature neonates the dosage may need to be altered
- 10 mg vial
- reconstitute vial with 5mL of sterile water for injection to obtain a solution of 2mg/mL
Example of a Calculation
- Baby's weight = 1.73 kg
Dose = 0.08 mg/kg
Dose = (0.08 mg/kg) (1.73 kg) = 0.1384 mg
Concentration, after reconstitution = 2 mg/mL
therefore, 0.1384 mg in 0.069 mL (Round off to 0.07mL)
THEREFORE, WITHDRAW 0.07mL OF THE 2mg/mL SOLUTION
CONTINUOUS IV INFUSION
Proceed only after steps 1) and 2) under "Continuous IV infusion" have been completed.
Initial vecuronium infusion rate = 1 mcg/kg/min
Baby's weight = 1.73 kg
Assume an infusion rate of 1 mL/h
1 mcg/kg/min = 1.73 mcg/min (for a 1.73 kg baby) = 103.8 mcg/h
Therefore, there will be 103.8 mcg in 1mL (ie. 1 hour's supply)
Therefore, there will be 5190 mcg (5.19 mg) in 50mL
PREPARATION OF MINIBAG
- Withdraw 7.6 mL from a 50 mL minibag. (There is an average of 5 mL OVERFILL in the minibags; also, 2.6 mL of drug will be injected into the minibag)
- Add 2.6 mL of reconstituted vecuronium (2 mg/mL) to the minibag (need 5.19 mg of drug)
- Mix minibag well. Run infusion at 1 mL/h.
- McEvoy G K (ed): AHFS Drug Information, American Society of Hospital Pharmacists, 1991.
- Drugs Dex, Denver, Colorado, 1992.
- Pagliaro LA and Pagliaro AM (ed): Problems in Pediatric Drug Therapy, 1987, Drug Intelligence Publ Inc, Hamilton, Illinois.
- Krogh CME et al (ed): Compendium of Pharmaceuticals and Specialties, Canadian Pharmaceutical Association, 1992.
- Milan EM and McFeely EJ: Memory Bank for Neonatal Drugs, 1990, Williams and Wilkins, Baltimore.
- Bhatt DR, Furman GI, Reber DJ et al: Neonatal Drug Formulary, 1990-1991, 2nd Edition, Fontana, California 92334.