isoproterenol hydrochloride

isoproterenol hydrochloride

[ī′sōprəter′ənol]

a beta-adrenergic stimulant.

indications It is used as a bronchodilator and as a cardiac stimulant.

contraindications Cardiac arrhythmia or known hypersensitivity to this drug prohibits its use.

adverse effects Among the more serious adverse effects are arrhythmias, tachycardia, hypotension, and intensification of angina.

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isoproterenol hydrochloride

Isuprel

Pharmacologic class: Sympathomimetic, beta₁-adrenergic and beta₂-adrenergic agonist

Therapeutic class: Vasopressor, bronchodilator, antiasthmatic

Pregnancy risk category C

Action

Acts on beta₂-adrenergic receptors, causing relaxation of bronchial smooth muscle; acts on beta₁-adrenergic receptors in heart, causing positive inotropic and chronotropic effects and increasing cardiac output. Also lowers peripheral vascular resistance in skeletal muscle and inhibits antigen-induced histamine release.

Availability

Injection: 20 mcg/ml, 200 mcg/ml

⊘Indications and dosages

➣ Shock

Adults and children: 0.5 to 5 mcg/minute by continuous I.V. infusion

➣ Heart block; ventricular arrhythmias

Adults: Initially, 0.02 to 0.06 mg I.V., then 0.01 to 0.2 mg I.V. or 5 mcg/minute I.V. Or initially, 0.2 mg I.M., then 0.02 to 1 mg I.M., depending on response. Or initially, 0.2 mg subcutaneously, then 0.15 to 0.2 mg subcutaneously, depending on response.

➣ Bronchospasm during anesthesia

Adults: 0.01 to 0.02 mg I.V., repeated when necessary

➣ Status asthmaticus

Children: 0.08 to 1.7 mcg/kg/minute by I.V. infusion

Contraindications

• Angina pectoris
• Angle-closure glaucoma
• Tachyarrhythmias
• Tachycardia or heart block caused by digitalis intoxication
• Ventricular arrhythmias that warrant inotropic therapy
• Labor, delivery, breastfeeding

Precautions

Use cautiously in:
• renal impairment, unstable vasomotor disorders, hypertension, coronary insufficiency, chronic obstructive pulmonary disease, diabetes mellitus, hyperthyroidism
• history of cerebrovascular accident or seizures
• elderly patients.

Administration

• Give each 0.02-mg I.V. dose by direct injection over 1 minute, or by I.V. infusion, as ordered. Always use continuous infusion pump to deliver infusion.

Route	Onset	Peak	Duration
I.V.	Immediate	Unknown	<1 hr
I.M.	Unknown	Unknown	Unknown
Subcut.	Immediate	Unknown	2 hr

Adverse reactions

CNS: tremors, anxiety, insomnia, headache, dizziness, asthenia

CV: palpitations, tachycardia, angina, rapid blood pressure changes, arrhythmias, cardiac arrest, Stokes-Adams attacks

EENT: pharyngitis

GI: nausea, vomiting, heartburn

Metabolic: hyperglycemia

Respiratory: bronchitis, increased sputum, pulmonary edema, bronchospasm

Skin: diaphoresis

Other: parotid gland swelling (with prolonged use)

Interactions

Drug-drug. Cyclopropane, epinephrine, halogenated general anesthetics: increased risk of arrhythmias

Propranolol, other beta-adrenergic blockers: antagonism of bronchodilating effects

Drug-diagnostic tests. Glucose: increased level

Patient monitoring

• During I.V. administration, monitor ECG and vital signs carefully.
• Assess patient's response to drug and adjust I.V. infusion rate accordingly.
• Closely monitor arterial blood gas values, urine output, and central venous pressure.
☞ Stay alert for rebound bronchospasm.

Patient teaching

• Assure patient that he'll be monitored closely.