DrugindexOnline^{2nd edition}

Pronouncation: (eye-so-pro-TER-uh-nahl)
Class: Vasopressor used in shock Isoproterenol Hydrochloride

Trade Names:
Isuprel
- Injection (1:5,000 solution) 0.2 mg/mL isoproterenol hydrochloride

Trade Names:
Isoproterenol Hydrochloride
- Injection (1:5,000 solution) 0.2 mg/mL isoproterenol hydrochloride
- Injection (1:50,000) 0.02 mg/mL isoproterenol hydrochloride

Isoproterenol Sulfate

Trade Names:
Medihaler-ISO
- Aerosol Delivers 80 mcg isoproterenol sulfate/actuation

Mechanism of Action

Pharmacology

Produces bronchodilation by relaxing bronchial smooth muscle through beta-2 receptor stimulation; increases heart rate and myocardial contractility by stimulating cardiac beta-1 receptors, which increases cardiac output.

Pharmacokinetics

Onset

Within 5 minutes.

Peak

Five to 15 minutes.

Duration

Less than 3 hours.

Indications and Usage

Management of bronchospasm during anesthesia; adjunctive treatment for shock.

Contraindications

Cardiac arrhythmias associated with tachycardia; tachycardia or heart block caused by digitalis intoxication; angina; ventricular arrhythmias requiring inotropic therapy.

Dosage and Administration

Bronchospasm during anesthesia
Adults

IV 0.01 to 0.02 mg. Repeat as necessary.

Shock and hypoperfusion
Adults

IV 0.5 mcg to 5 mcg/min. Rates over 30 mcg/min have been used in advanced stages of shock.

Heart block, Adams-Stokes attacks, and cardiac arrest
Adults

Bolus IV 0.02 mg to 0.06 mg initial dose with subsequent dose range of 0.01 mg to 0.2 mg; IV infusion 5mcg/min initial dose; IM 0.2 mg initial dose with a subsequent dose rang of 0.02 mg to 1 mg; Subcutaneous 0.2 mg initial dose of 0.2 mg with subsequent dose range of 0.15 mg to 0.2 mg; Intracardiac 0.02 mg initial dose. Subsequent dosage and administration method depend on ventricular rate and rapidity with which cardiac pacemaker can take over when drug is withdrawn.

General Advice

IV injection

Dilute 1 mL of 1:5,000 solution to 10 mL with sodium chloride 5% or dextrose injection to achieve 1:50,000 solution.

IV infusion

Dilute 10 mL 1:5,000 solution in 500 mL 5% Dextrose to produce 1:250,000 solution. Use microdrip or continuous infusion pump to prevent sudden influx of large amount of drug.

Metered dose inhaler

Shake container thoroughly before use.

Storage/Stability

Store in tight, light-resistant container at room temperature.

Drug Interactions

Cardiac glycosides

Arrhythmias may result with coadministration.

General anesthetics (eg, halothane, cyclopropane)

Arrhythmias may result with coadministration.

Ergot alkaloids

Coadministration may result in additive peripheral vasoconstriction.

Laboratory Test Interactions

Bilirubin may be falsely elevated if measured by sequential multiple analyzer. Urinary epinephrine values may be elevated.

Adverse Reactions

Cardiovascular

Palpitations; tachycardia; BP changes; arrhythmias; Adams-Stokes attacks; cardiac arrest.

CNS

Tremor; dizziness; nervousness; drowsiness; headache; insomnia.

GI

Nausea; GI distress.

Respiratory

Cough; throat irritation; bronchitis; sputum increase; pulmonary edema.

Miscellaneous

Parotid gland swelling with prolonged use; saliva discoloration; sweating; skin flushing.

Precautions

Pregnancy

Category C .

Lactation

Undetermined.

Children

Safety and efficacy have not been established.

Elderly

Lower doses may be required.

Labor and Delivery

May inhibit uterine contractions and delay preterm labor.

Cardiogenic shock

Isoproterenol hydrochloride injection, by increasing myocardial oxygen requirements while decreasing effective coronary perfusion, may have a deterious effect on the injured or failing heart. Most experts discourage its use as the initial agent in treating cardiogenic shock following myocardial infarction.

CV disorders

Toxic symptoms in patients with CV disorders may occur. Doses sufficient to increase the heart rate more than 130 bpm may induce ventricular arrhythmias. Use with caution in patients with coronary artery disease, coronary insufficiency, diabetes, or hyperthyroidism, and in patients sensitive to sympathomimetic amines.

Hypovolemia

Adequate filling of the intravascular compartment by suitable volume expanders is of primary importance in most cases of shock and should precede the administration of vasoactive drugs.

Refractory asthmatic children

IV infusions of isoproterenol have caused clinical deterioration, myocardial necrosis, CHF, and death.

Overdosage

Symptoms

Tremor, palpitations, angina, arrhythmias, tachycardia, elevated or decreased BP, seizures, nervousness, headache, dry mouth, nausea, dizziness, fatigue, malaise, insomnia.

Patient Information

• Use verbal instructions and demonstrations to teach technique for inhalation therapy and explain that if more than 1 inhalation is necessary, patient should wait 3 to 5 min between doses.
• Tell patient to notify health care provider if no response to usual dose.

• Monitor heart rate, respirations, BP, and urine output. Carefully monitor heart rate and rhythm and ECG pattern when used as treatment for shock.