ISOETHARINE HYDROCHLORIDE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ISOETHARINE HYDROCHLORIDE (ISOETHARINE HYDROCHLORIDE).
ISOETHARINE HYDROCHLORIDE is a beta-2 adrenergic receptor agonist that stimulates adenylate cyclase, increasing cyclic AMP (cAMP) in bronchial smooth muscle, leading to bronchodilation. It also has beta-1 activity at higher doses, causing cardiac stimulation.
| Metabolism | Metabolized primarily via catechol-O-methyltransferase (COMT) and sulfotransferases in the liver and other tissues. |
| Excretion | Primarily renal excretion of unchanged drug and metabolites; approximately 60-80% of a dose is excreted in urine within 24 hours, with the remainder excreted in feces via biliary elimination. |
| Half-life | 1.6 to 2.7 hours in adults; may be prolonged in patients with hepatic or renal impairment. |
| Protein binding | Approximately 20-30% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Approximately 0.5 L/kg, indicating distribution into total body water. |
| Bioavailability | Inhalation: 10-20% (high first-pass hepatic metabolism for swallowed portion); subcutaneous: 100%. |
| Onset of Action | Inhalation: 1-5 minutes; subcutaneous: 5-15 minutes. |
| Duration of Action | Inhalation: 1-3 hours; subcutaneous: 2-4 hours. Tolerance may develop with prolonged use. |
Inhalation via nebulizer: 0.5 mL (2.5 mg) of 0.5% solution diluted in 2-3 mL normal saline, administered over 10-20 minutes, every 4-6 hours as needed.
| Dosage form | SOLUTION |
| Renal impairment | No specific dose adjustment required; primarily metabolized in liver, renal excretion limited. |
| Liver impairment | No specific guidelines; use with caution in severe hepatic impairment due to potential for reduced clearance. |
| Pediatric use | Inhalation via nebulizer: 0.01-0.02 mL/kg of 0.5% solution (max 0.5 mL) diluted in 2-3 mL normal saline, every 4-6 hours as needed. |
| Geriatric use | Consider lower initial doses due to potential for increased sensitivity and concomitant conditions; monitor for cardiac effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ISOETHARINE HYDROCHLORIDE (ISOETHARINE HYDROCHLORIDE).
| Breastfeeding | Excreted in breast milk in small amounts; unlikely to cause adverse effects in infant. M/P ratio not established. Caution with high maternal doses. |
| Teratogenic Risk | Animal studies have not been conducted; no adequate human studies. Beta-agonists may cause fetal tachycardia and hypoglycemia. Use only if clearly needed. First trimester: avoid if possible. Second/third trimester: may cause uterine relaxation, delay labor. |
| Fetal Monitoring |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to isoetharine or any component","Cardiac arrhythmias associated with tachycardia","Pre-existing cardiac disease (e.g., coronary insufficiency, hypertension) when risk outweighs benefit"]
| Precautions | ["Cardiovascular effects: May cause tachycardia, palpitations, hypertension, or arrhythmias; use with caution in patients with coronary insufficiency, cardiac arrhythmias, or hypertension.","Paradoxical bronchospasm: Discontinue immediately if occurs.","Hypersensitivity reactions: Possible anaphylaxis.","Deterioration of asthma: Need reassessment if symptoms worsen.","Immediate hypersensitivity reactions: Urticaria, angioedema, rash."] |
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| Monitor maternal heart rate, blood pressure, serum glucose, and potassium. Fetal heart rate monitoring during prolonged use. Assess for signs of pulmonary edema with concomitant corticosteroids. |
| Fertility Effects | No known adverse effects on fertility. Beta-agonists may transiently affect ovulation in animal studies, but clinical significance unknown. |