Mivacurium Chloride

 Action Binds competitively to cholinergic receptors on motor end-plate to antagonize action of acetylcholine, resulting in block of neuromuscular transmission.

 Indications Adjunct to general anesthesia; facilitation of tracheal intubation.

 Contraindications Hypersensitivity to mivacurium or similar agents; use of multidose vials in benzyl alcohol-sensitive patients.

 Route/Dosage

ADULTS: IV Initial dose: 0.15 mg/kg over 5–15 sec. Maintenance: 0.1 mg/kg q 15 min prn or 9–10 mcg/kg/min infusion initially followed by titration (range 1–15 mg/kg/min). CHILDREN 2–12 YR: IV Initial dose: 0.2 mg/kg over 5–15 sec. Maintenance: 14 mcg/kg/min infusion initially followed by titration (range 5–31 mcg/kg/min).

 Interactions

Aminoglycosides, clindamycin, inhalation anesthetics ketamine, parenteral magnesium salts, polypeptide antibiotics, quinidine, quinine, trimethaphan, verapamil: Action of mivacurium potentiated. Azathioprine: Action of mivacurium may be decreased or reversed. Carbamazepine: Shortened action of mivacurium and decreased effectiveness. Theophyllines: Dose-dependent reversal of neuromuscular blockade. Trimethaphan: Prolonged apnea. Verapamil: Enhanced action of mivacurium (eg, respiratory depression). INCOMPATIBILITIES: Alkaline solutions (pH > 8.5).

 Lab Test Interferences None well documented.

 Adverse Reactions

CV: Flushing; hypotension; tachycardia; bradycardia; arrhythmia; hlebitis. DERM: Rash; urticaria; erythema; injection site reaction. RESP: Bronchospasm; wheezing; hypoxemia. OTHER: Dizziness; muscle spasms.

 Precautions

Pregnancy: Category C. Lactation: Undetermined. Children: Safety and efficacy in children < 2 yr not established. Elderly patients: Neuromuscular blockade may be longer. Cachectic or debilitated patients, patients with neuromuscular disease, burns: Use test dose of £ 0.015–0.02 mg/kg. Cardiovascular disease or allergy/sensitivity (eg, asthma): Administer initial dose of £ 0.15 mg/kg over 60 sec. Obese patients: Use ideal body weight to determine initial dose. Reduced plasma cholinesterase activity: Use drug with great caution, if at all. Renal and hepatic impairment: Duration of action is longer; use lower maintenance doses.

 Administration/Storage

• Administer via IV route only.
• Administer only under supervision of health care provider familiar with drug actions and possible complications.
• Ensure that personnel and facilities for resuscitation and life support (tracheal intubation, artificial ventilation, oxygen therapy) re available and have antagonist of drug (anticholinesterase) immediately available.
• Administer to unconscious patients only.
• Prepared drug dilutions in compatible solutions may be stored at room temperature for up to 24 hr when protected from ultraviolet light and from temperature extremes.
• Do not introduce additives into infusion solution.
• Discard unused portion of diluted drug after each use.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies. Note cardiovascular disease, asthma or other conditions resulting in sensitivity to release of histamine or related mediators; neuromuscular disease; carcinomatosis; renal or hepatic impairment; history of reduced plasma cholinesterase activity.
• Observe for flushing, hypotension, increases or decreases in heart rate, dizziness or muscle spasms and report to physician.
• Use nerve stimulator to assess neuromuscular blockade.
• Maintain adequate hydration and monitor hemodynamic status in patients with clinically significant cardiovascular disease and with asthma or other conditions resulting in sensitivity to release of histamine or related mediators.
• Perform eye care (eg, artificial tears, covering eye) frequently to prevent corneal drying.

 Patient/Family Education

• Explain that drug will be administered while patient is unconscious.
• Advise patient that dizziness or muscle spasms sometimes occur during recovery.