ISUPREL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ISUPREL (ISUPREL).
Nonselective beta-adrenergic agonist with predominant beta-1 and beta-2 receptor stimulation, leading to increased heart rate, contractility, and bronchodilation.
| Metabolism | Metabolized primarily by catechol-O-methyltransferase (COMT) in the liver and other tissues; undergoes sulfation and glucuronidation. |
| Excretion | Primarily renal excretion of unchanged drug and conjugates; approximately 50-70% excreted in urine within 24 hours (mostly as sulfate conjugates, with about 10-15% unchanged), and less than 5% in feces. |
| Half-life | Terminal elimination half-life is approximately 2.5-3 hours in adults. In neonates and infants, half-life may be longer (up to 6-8 hours). Clinical context: Short half-life necessitates continuous infusion for sustained effect in acute settings. |
| Protein binding | Approximately 50-60% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Approximately 0.4-0.6 L/kg in adults. Clinical meaning: Moderate distribution indicates drug is not extensively sequestered in tissues; equilibrium between plasma and interstitial fluid. |
| Bioavailability | Not available for oral route (extensive first-pass metabolism). Sublingual: Variable, less than 10%. Inhalation: Variable, depends on device and technique, typically 5-15%. |
| Onset of Action | IV: Immediate (within 30 seconds). IM: Within 10-15 minutes. Subcutaneous: Within 15-30 minutes. Inhalation (aerosol): Within 1-3 minutes. |
| Duration of Action | IV: Very short (1-5 minutes due to rapid redistribution and metabolism). IM/SC: 30-60 minutes. Inhalation: 1-2 hours. Clinical note: Effects dissipate quickly; continuous IV infusion often needed for prolonged beta-adrenergic stimulation. |
Adult: 0.5-5 mcg/min IV infusion titrated to effect; bolus: 10-20 mcg IV push. Sublingual: 10-20 mg 3-4 times daily.
| Dosage form | INJECTABLE |
| Renal impairment | No specific dose adjustment required; use with caution in severe renal impairment (CrCl <30 mL/min) due to potential accumulation. |
| Liver impairment | No specific dose adjustment; based on Child-Pugh class: mild (A) no adjustment, moderate (B) reduce initial dose by 50%, severe (C) avoid use or reduce by 75%. |
| Pediatric use | Initial IV infusion: 0.1-1 mcg/kg/min, titrate to response. Max: 2 mcg/kg/min. Bolus: 0.5-1 mcg/kg IV push. |
| Geriatric use | Start at lower end of dosing range (0.5-1 mcg/min IV), titrate slowly due to increased sensitivity and risk of arrhythmias. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ISUPREL (ISUPREL).
| Breastfeeding | Isoproterenol is excreted into breast milk in small amounts. M/P ratio is unknown. Limited data suggest minimal risk to the nursing infant due to rapid metabolism and poor oral bioavailability. However, avoid breastfeeding during IV administration due to potential for infant exposure. Use with caution and monitor infant for signs of beta-adrenergic stimulation (tachycardia, irritability). |
| Teratogenic Risk | Isuprel (isoproterenol) is a beta-adrenergic agonist. Data on human pregnancy are limited. Animal studies have not been reported. First trimester: No documented fetal abnormalities; theoretical risk of fetal tachycardia. Second/third trimesters: May cause maternal tachycardia, palpitations, and uterine relaxation; potential for fetal hypoxia due to reduced uterine blood flow. Avoid use during labor as it may inhibit uterine contractions and delay delivery. Categorized as FDA Pregnancy Category C. |
■ FDA Black Box Warning
None.
| Serious Effects |
["Hypersensitivity to isoproterenol or any component.","Tachyarrhythmias (e.g., ventricular tachycardia) unless due to heart block.","Patients with angina pectoris (due to increased myocardial oxygen demand).","Concurrent use with general anesthetics that sensitize the myocardium to catecholamines (e.g., halothane)."]
| Precautions | ["May cause serious cardiac arrhythmias, including ventricular fibrillation, especially in patients with pre-existing heart disease.","Caution in patients with coronary artery disease, hypertension, or hyperthyroidism.","May produce paradoxical bronchospasm if used excessively.","Use with caution in patients with diabetes (may increase blood glucose)."] |
| Food/Dietary | No significant food interactions known for intravenous isoproterenol. |
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| Fetal Monitoring | Monitor maternal heart rate, blood pressure, ECG, and serum potassium. Assess fetal heart rate and uterine activity during infusion. Watch for signs of maternal myocardial ischemia, arrhythmias, or hypotension. In pregnancy, monitor for decreased uterine perfusion and fetal distress via Doppler or continuous fetal monitoring. |
| Fertility Effects | No specific human studies on fertility. Animal studies have not reported adverse effects on fertility. Theoretical concern based on beta-adrenergic activity may alter reproductive hormone levels, but clinical significance is unknown. |
| Clinical Pearls | ISUPREL (isoproterenol) is a non-selective beta-adrenergic agonist used primarily for bradycardia and heart block. It increases heart rate and contractility but can cause hypotension due to peripheral vasodilation. Monitor for arrhythmias. Use with caution in ischemic heart disease, hyperthyroidism, and diabetes. Tolerance may develop with prolonged use. |
| Patient Advice | This medication is given intravenously in a hospital setting. · You will be monitored closely for heart rate and blood pressure changes. · Report any chest pain, palpitations, or shortness of breath immediately. · Do not stop taking this medication abruptly without medical advice. |