From the Guidelines
Isoproterenol should be used with caution in emergency situations for severe bradycardia, heart block, or torsades de pointes when other interventions have failed, due to its potential to increase myocardial oxygen demand and worsen ischemia in patients with coronary artery disease, as noted in the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1.
Clinical Uses
Isoproterenol is a non-selective beta-adrenergic agonist that can be used in the following clinical scenarios:
- Severe bradycardia
- Heart block
- Torsades de pointes It is typically administered intravenously at 1-20 mcg/min, titrated to desired heart rate response, as outlined in the 2018 ACC/AHA/HRS guideline 1.
Precautions
Major precautions include:
- Avoiding use in patients with coronary artery disease, as it significantly increases myocardial oxygen demand and can worsen ischemia
- Using cautiously in patients with hypertension, diabetes, hyperthyroidism, or arrhythmias Common adverse effects include:
- Tachycardia
- Palpitations
- Headache
- Tremor
- Anxiety Isoproterenol can also cause hypotension due to peripheral vasodilation.
Administration
Continuous cardiac monitoring is essential during administration, and the drug should be used for the shortest duration necessary, as recommended in the 2018 ACC/AHA/HRS guideline 1. It has largely been replaced by more selective agents in many clinical scenarios but remains valuable in specific emergency situations where rapid chronotropic effects are needed. The dosage of isoproterenol can be adjusted based on heart rate response, with a typical range of 1-20 mcg/min, as outlined in the 2018 ACC/AHA/HRS guideline 1. In summary, isoproterenol is a valuable agent in emergency situations, but its use requires careful consideration of the potential risks and benefits, particularly in patients with coronary artery disease, as noted in the 2018 ACC/AHA/HRS guideline 1.
From the FDA Drug Label
Isoproterenol Hydrochloride Injection is indicated: To improve hemodynamic status in patients in distributive shock and shock due to reduced cardiac output For bronchospasm occurring during anesthesia
The clinical uses of Isoproterenol (isoproterenol hydrochloride) are:
- To improve hemodynamic status in patients with distributive shock and shock due to reduced cardiac output
- For bronchospasm occurring during anesthesia
The precautions for Isoproterenol (isoproterenol hydrochloride) are:
- Cardiac Arrhythmias and Ischemia: Isoproterenol may induce cardiac arrhythmias and myocardial ischemia in patients, especially patients with coronary artery disease, or cardiomyopathy 2
- Allergic Reactions associated with Sulfite: Isoproterenol Hydrochloride Injection contains sodium metabisulfite, which may cause mild to severe allergic reactions including anaphylaxis or asthmatic episodes, particularly in patients with a history of allergies 2
- Contraindications: Isoproterenol Hydrochloride Injection is contraindicated in patients with tachycardia, ventricular arrhythmias, and angina pectoris 2 2
From the Research
Clinical Uses of Isoproterenol
- Isoproterenol is used in the treatment of severe asthma, including status asthmaticus in children 3 and adults 4, 5.
- It is effective in reversing increased PCO2 and impending respiratory failure in status asthmaticus 3.
- Isoproterenol can be administered intravenously or through continuous inhalation therapy 3, 4, 5.
- It has a prompt onset and offset of effects, making it a useful option for patients who do not respond to conventional therapy 4, 5.
Precautions and Side Effects
- Isoproterenol can cause arrhythmias, and its use should be closely monitored in patients with cardiac conditions 3.
- It can also cause an increase in heart rate and blood pressure, particularly at higher doses 4, 5.
- Rebound bronchospasm can occur when isoproterenol is abruptly discontinued 3.
- Isoproterenol should be used with caution in patients with hypertension, and its use should be avoided in patients with certain cardiac conditions 4, 5.
Comparison with Other Bronchodilators
- Isoproterenol has been compared to other bronchodilators, such as ipratropium bromide, and has been shown to have similar bronchodilator effects 6.
- However, ipratropium bromide has a longer duration of action and is free of significant side effects 6.
- The mechanism of action of isoproterenol involves reducing airway wall stiffness, which enhances the bronchodilatory response to breathing maneuvers 7.