TUBOCURARINE CHLORIDE

(too-boe-kyoo-ar'een)
Tubocurarine Chloride
Classifications: autonomic nervous system agent; nondepolarizing skeletal muscle relaxant
Pregnancy Category: C

Availability

3 mg/mL injection

Actions

Curare alkaloid that is a nondepolarizing neuromuscular blocking agent extracted from the plant Chondodendron tomentosum. Produces skeletal muscle relaxation or paralysis by competing with acetylcholine at cholinergic receptor sites on skeletal muscle endplate and thus blocks nerve impulse transmission. Also has histamine-releasing and ganglionic blocking properties.

Therapeutic Effects

Blocks nerve impulse transmission to skeletal muscles, thus producing relaxation or paralysis of skeletal muscles. Utilized with general anesthesia and as an adjunct to mechanical ventilation.

Uses

To induce skeletal muscle relaxation as adjunct to general anesthesia, to facilitate management of mechanical ventilation, to reduce intensity of muscle contractions in tetanus and in pharmacologically or electrically induced convulsions, to treat spastic states in children, and for diagnosis of myasthenia gravis when conventional tests have been inconclusive.

Contraindications

Hypersensitivity to curare preparations; when histamine release is a hazard; hyperthermia; electrolyte imbalance; acidosis; neuromuscular disease; kidney disease. Safety during pregnancy (category C) or lactation is not established.

Cautious Use

Impaired cardiovascular, kidney, liver, pulmonary, or endocrine function; hypotension; carcinomatosis; thyroid disorders; collagen diseases; porphyria; familial periodic paralysis; history of allergies; myasthenia gravis; older adults or debilitated patients.

Route & Dosage

Adjunct to General Anesthesia
Adult: IV 6–9 mg followed by 3–4.5 mg in 3–5 min if necessary
Child: IV 0.2–0.5 mg/kg followed by 0.04–0.1 mg/kg prn to maintain paralysis
Neonate: IV <1 mo, 0.3 mg/kg followed by 0.1 mg/kg prn to maintain paralysis

Electroshock
Adult: IV 0.165 mg/kg administered slowly IV

Diagnosis of Myasthenia Gravis
Adult: IV 0.004–0.033 mg/kg

Administration

Note: Verify correct IV dilution and rate of IV injection for neonates, infants, children with physician.

Intravenous

PREPARE: IV Infusion: May be given undiluted (3 mg/mL).

ADMINISTER: IV Infusion: Give bolus dose over 60–90 sec.

INCOMPATIBILITIES Solution/additive: barbiturates, sodium bicarbonate; trimethaphan.

Do not use solutions of drug if more than faintly discolored.
Do not mix in same syringe with solutions that have a high pH such as barbiturates and sodium bicarbonate.

Adverse Effects (1%)

Body as a Whole: Slight dizziness, feeling of warmth, malignant hyperthermia, hypersensitivity reactions. Musculoskeletal: Profound and prolonged muscle weakness and flaccidity. Respiratory: Respiratory depression, hypoxia, apnea, increased bronchial and salivary secretions, bronchospasm. GI: Decreased GI motility. CV: Hypotension, circulatory collapse.

Interactions

Drug: skeletal muscle relaxants, inhaled anesthetics, aminoglycosides, polymyxin B, clindamycin, quinidine, quinine, procainamide, diuretics, amphotericin B may potentiate neuromuscular blockade.

Pharmacokinetics

Peak: 2–5 min. Duration: 20–30 min if used alone. Metabolism: Demethylated in liver. Elimination: 33–75% excreted in urine within 24 h; 11% excreted in bile; crosses placenta. Half-Life: 1–3 h.

Nursing Implications

Assessment & Drug Effects

Lab tests: Obtain baseline kidney function and determinations of serum electrolytes. Electrolyte imbalance (particularly potassium and magnesium) can potentiate the effects of nondepolarizing neuromuscular blocking agents.
Monitor BP, vital signs, and airway until assured of patient's recovery from drug effects. Ganglionic blockade (hypotension) and histamine liberation (increased salivation, bronchospasm) and neuromuscular blockade (respiratory depression) are known effects of tubocurarine.
Be aware that selective muscle paralysis following drug administration occurs in the following sequence: jaw muscles, levator eyelid muscles and other muscles of head and neck, limbs, intercostals and diaphragm, abdomen, trunk. Facial and diaphragm muscles are first to recover, followed in order by legs, arms, shoulder girdle, trunk, larynx, hands, feet, pharynx. Muscle function is usually restored within 90 min.
Measure and record I&O ratio during day of drug administration. Renal dysfunction will prolong drug action. Peristaltic action may be suppressed. Check for bowel sounds.

Patient & Family Education

Note: Tubocurarine is retained in the body long after effects of neuromuscular blockade appear to have dissipated. Report residual muscle weakness to physician.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug