isoproterenol hydrochloride
isoproterenol hydrochloride
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
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.
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Adverse reactions
CNS: tremors, anxiety, insomnia, headache, dizziness, asthenia, nervousness
CV: palpitations, tachycardia, angina, rapid blood pressure changes, arrhythmias, cardiac arrest, Stokes-Adams attacks
EENT: pharyngitis, visual blurring
GI: nausea, vomiting, heartburn
Metabolic: hyperglycemia
Respiratory: bronchitis, dyspnea, increased sputum, pulmonary edema, bronchospasm
Skin: diaphoresis
Other: parotid gland swelling (with prolonged use), pallor
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.
See Stay alert for rebound bronchospasm.
Patient teaching
• Assure patient that he'll be monitored closely.