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Action/Kinetics:
Competitively inhibits the action of acetylcholine on the motor end plate, resulting in a block of neuromuscular transmission. Time to maximum neuromuscular blockade is similar to atracurium (2.3-4.9 min in adults depending on the dose and 1.6-2.8 min in children depending on the dose).
Clinically effective neuromuscular block, adults: 15-20 min after 0.15 mg/kg;
children: 6-15 min after 0.2 mg/kg. Spontaneous recovery may be 95% complete in 25-30 min after an initial dose of 0.15 mg/kg in adults during opioid/nitrous oxide/oxygen anesthesia. Repeated administration or continuous infusion (for up to 2.5 hr) does not cause tachyphylaxis or cumulative neuromuscular blockade. Higher doses may cause transient decreases in mean arterial BP (especially seen in obese clients) and increases in HR in some clients within 1-3 min following the dose (can be minimized by giving the drug over 30-60 sec). The product is actually a mixture of isomers with varying elimination half-lives. Inactivated by plasma cholinesterase with metabolites excreted in the urine and bile.
Uses:
Adjunct to general anesthesia to facilitate tracheal intubation and to provide relaxation of skeletal muscle during surgery or mechanical ventilation.
Contraindications:
Sensitivity to mivacurium or other similar agents. Use of multidose vials in clients with allergy to benzyl alcohol.
Special Concerns:
Use with caution during lactation, in clients with significant CV disease, and in those with any history of a greater sensitivity to the release of histamine or related mediators such as asthma. Volatile anesthetics may decrease the dosing requirement and prolong the duration of action. Duration may be prolonged in clients with decreased plasma cholinesterase. Reduced clearance of one or more isomers is observed in clients with end-stage kidney or liver disease. Geriatric clients show a longer duration of neuromuscular blockade. Acid-base or serum electrolyte abnormalities may potentiate or antagonize the action of neuromuscular blocking agents. Antagonism of neuromuscular blockade may be delayed in the presence of debilitation, carcinomatosis, and concomitant use of certain broad-spectrum antibiotics, anesthetic agents, and other drugs that enhance neuromuscular blockade. In children 2-12 years of age, mivacurium has a faster onset, shorter duration, and a faster recovery following reversal than adults. The drug has not been studied in children less than 2 years of age.
Side Effects:
Neuromuscular: Prolonged neuromuscular blockade, muscle spasms.
CV: Flushing of face, neck, or chest; hypotension, tachycardia, bradycardia, cardiac arrhythmias, phlebitis.
Respiratory:
Bronchospasm wheezing, hypoxemia.
Dermatologic: Rash, urticaria, erythema, reaction at injection site.
CNS: Dizziness.
Overdose Management:
Symptoms: Neuromuscular blockade beyond the time needed for surgery and anesthesia. Increased risk of hemodynamic side effects such as hypotension.
Treatment:
- Primary treatment is maintenance of a patent airway and controlled ventilation until there is recovery of normal neuromuscular function.
- Neostigmine (0.03-0.064 mg/kg) or edrophonium (0.5 mg/kg) can be given once there is evidence of recovery from neuromuscular blockade.
- A peripheral nerve stimulator can be used to assess recovery and antagonism of neuromuscular block.
Drug Interactions:
See
Neuromuscular Blocking Agents
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Also, there is enhanced neuromuscular blockade when magnesium is given to pregnant women for toxemia.
How Supplied:
Injection: 2 mg/mL
Dosage
?IV Only
Facilitation of tracheal intubation.
Adults: 0.15 mg/kg given over 5-15 sec. Maintenance doses of 0.1 mg/kg provide about 15 min of additional clinically effective blockade.
Children, 2-12 years: The dosage requirements on a mg/kg basis are higher in children and onset and recovery occur more rapidly.
Initial: 0.2 mg/kg given over 5-15 sec.
Facilitation of tracheal intubation using continuous IV infusion.
Continuous IV infusion may be used to maintain neuromuscular block.
Adults: On evidence of spontaneous recovery from an initial dose, an initial infusion rate of 9-10 mcg/kg/min is recommended. If continuous infusion is started at the same time as the administration of an initial dose, use a lower initial infusion rate (such as 4 mcg/kg/min). In either case, adjust the initial infusion rate according to the response to peripheral nerve stimulation and to clinical criteria. An average infusion rate of 6-7 mcg/kg/min will maintain neuromuscular block within the range of 89%-99% for extended periods of time in adults receiving opioid/nitrous oxide/oxygen anesthesia.
Children: Require higher infusion rates. During opioid/nitrous oxide/oxygen anesthesia, the infusion rate needed to maintain 89%-99% blockade averages 14 mcg/kg/min (range: 5-31 mcg/kg/min).
Tracheal intubation in clients with renal or hepatic impairment.
0.15 mg/kg. Infusion rates should be decreased by as much as 50% in these clients depending on the degree of renal or hepatic impairment.
Use in clients with reduced cholinesterase activity.
Initial doses greater than 0.03 mg/kg are not recommended.
Use in clients who are cachectic, are debilitated, or have carcinomatosis or neuromuscular disease.
A test dose of 0.015-0.02 mg/kg is recommended.
Use with isoflurane or enflurane anesthesia.
An initial dose of 0.15 mg/kg may be used for intubation prior to administration of the isoflurane or enflurane. If mivacurium is given after establishment of anesthesia, reduce the initial dose by as much as 25% and decrease the infusion rate by as much as 35%-40%. When used with halothane, no adjustment of the initial dose is necessary but decrease the infusion rate by as much as 20%.
Use in burn clients.
A test dose of not more than 0.015-0.02 mg/kg is recommended, followed by additional dosing guided by the use of a neuromuscular block monitor.
Use in obese clients weighing equal to or greater than 30% more than their ideal body weight (IBW).
The initial dose is calculated using the IBW according to the following formulas:
Men: IBW in kg = (106 + [6 x height in inches above 5 ft])/2.2
Women: IBW in kg = (100 + [5 x height in inches above 5 ft])/2.2
Use in clients with clinically significant CV disease or in those with any history of a greater sensitivity to the release of histamine or related mediators (asthma).
An initial dose less than or equal to 0.15 mg/kg given over 60 sec.
