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Action/Kinetics:
Produces pronounced stimulation of both beta-1 and beta-2 receptors of the heart, bronchi, skeletal muscle vasculature, and the GI tract. Has both positive inotropic and chronotropic activity; systolic BP may increase while diastolic BP may decrease. Thus, mean arterial BP may not change or may be decreased. Causes less hyperglycemia than epinephrine, but produces bronchodilation and the same degree of CNS excitation.
Inhalation: Onset, 2-5 min;
peak effect: 3-5 min;
duration: 1-3 hr.
IV: Onset, immediate;
duration: less than 1 hr. Partially metabolized; excreted in urine.
Uses:
Inhalation: Relief of bronchospasms associated with acute and chronic asthma, chronic bronchitis, or emphysema.
Injection: Bronchospasm during anesthesia. As an adjunct to fluid and electrolyte replacement therapy to treat hypovolemic and septic shock, low cardiac output states, CHF, and cardiogenic shock. Mild or transient heart block that does not require electric shock or pacemaker therapy. For serious episodes of heart block and Adams-Stokes attacks, except when caused by ventricular tachycardia or fibrillation. Use in cardiac arrest until electric shock or pacemaker therapy are available.
Contraindications:
Tachyarrhythmias, tachycardia, or heart block caused by digitalis intoxication, ventricular arrhythmias that require inotropic therapy, and angina pectoris.
Special Concerns:
Use with caution during lactation and in the presence of tuberculosis. Safety and effectiveness have not been determined in children less than 12 years of age.
Additional Side Effects:
CV:
Cardiac arrest Adams-Stokes attack, hypotension, precordial pain or distress.
CNS: Hyperactivity, hyperkinesia.
Respiratory: Wheezing, bronchitis, increase in sputum,
bronchial edema and inflammation, pulmonary edema, paradoxical airway resistance. Excessive inhalation causes refractory bronchial obstruction.
Miscellaneous: Flushing, sweating, swelling of the parotid gland. Sublingual administration may cause buccal ulceration. Side effects of drug are less severe after inhalation.
Drug Interactions:
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Bretylium / Possibility of arrhythmias
Guanethidine /
Pressor response of isoproterenol
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Halogenated hydrocarbon anesthetics / Sensitization of the heart to catecholamines
serious arrhythmias
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Oxytocic drugs / Possibility of severe, persistent hypertension
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Tricyclic antidepressants / Potentiation of pressor effect
How Supplied:
Isoproterenol Hydrochloride:
Metered dose inhaler: 103 mcg/inh;
Injection: 0.02 mg/mL (1:50,000), 0.2 mg/mL (1:5000);
Solution for Inhalation: 0.5% (1:200), 1% (1:100).
Isoproterenol Sulfate:
Metered dose inhaler: 80 mcg/inh
Dosage
Isoproterenol hydrochloride
?Inhalation
Acute bronchial asthma.
Hand bulb nebulizer.
Adults and children: Give 5-15 deep inhalations of the 1:200 solution. Alternatively, in adults, give 3-7 deep inhalations of the 1:100 solution. If no relief occurs after 5-10 min, repeat doses once more. If acute attack recurs, can repeat treatment up to 5 times/day, if necessary.
Metered dose inhaler. One inhalation (103 mcg). Wait 1 min to determine effect before considering a second inhalation. Repeat up to 5 times/day, if necessary.
Bronchospasm in chronic obstructive lung disease.
Hand bulb nebulizer. Give 5-15 deep inhalations using the 1:200 solution. Severe attacks may require 3-7 inhalations using the 1:100 solution. Wait at least 3-4 hr between doses.
Nebulization by compressed air or oxygen. Dilute 0.5 mL of the 1:200 solution to 2-2.5 mL with appropriate diluent for a concentration of 1:800 to 1:1000. Deliver the solution over 10-20 min. May repeat up to 5 times/day.
Intermittent positive pressure breathing. Dilute 0.5 mL of the 1:200 solution to 2-2.5 mL with water or isotonic saline. Deliver over 15-20 min. May repeat up to 5 times/day.
Metered dose inhaler. 1 or 2 inhalations repeated at no less than 3-4 hr intervals (6-8 times/day).
Children: For acute bronchospasms, use the 1:200 solution. Do not use more than 0.25 mL of the 1:200 solution for each 10-15 min programmed treatment.
?IV
Bronchospasms during anesthesia.
Dilute 1 mL of a 1:5000 solution to 10 mL with NaCl injection or D5W.
Initial dose: 0.01-0.02 mg (0.5-1 mL of diluted solution). Repeat when necessary.
Hypovolemic and septic shock.
Start the 1:50,000 solution at the lowest recommended dose and increase the rate of administration gradually, while carefully monitoring.
Heart block, Adams-Stokes attacks, cardiac arrest.
IV injection. Dilute 1 mL of the 1:5000 solution (0.2 mg) to 10 mL with NaCl or D5W.
Initial dose: 0.02-0.06 mg (1-3 mL of diluted solution);
then 0.01-0.2 mg (0.5-10 mL of diluted solution).
IV infusion. Dilute 10 mL of the 1:5000 solution (2 mg) in 500 mL of D5W or dilute 5 mL of the 1:5000 solutoin (1 mg) in 250 mL of D5W.
Initial dose: 5 mcg/min (1.25 mL/min of diluted solution).
?IM
Heart block, Adams-Stokes attacks, cardiac arrest.
Initial: 0.2 mg (1 mL) of undiluted 1:5000 solution;
then 0.02-1 mg (0.1-5 mL) of undiluted 1:5000 solution.
?SC
Heart block, Adams-Stokes attacks, cardiac arrest.
Initial: 0.2 mg (1 mL) of undiluted 1:5000 solution;
then 0.15-0.2 mg (0.75-1 mL) of undiluted 1:5000 solution.
?Intracardiac
Emergency use in heart block, Adams-Stokes attacks, cardiac arrest.
Give 0.02 mg (0.1 mL) of the undiliuted 1:5000 solution.
Isoproterenol sulfate
?Inhalation
Acute bronchial asthma.
Initial: 1 inhalation (80 mcg). If no relief is evident after 2-5 min, a second inhalation may be given.
Maintenance: 1-2 inhalations 4-6 times/day. Do not give more than 2 inhalations at any one time and no more than 6 inhalations/hr.
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