BRETHAIRE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for BRETHAIRE (BRETHAIRE).
Beta-2 adrenergic receptor agonist; relaxes bronchial smooth muscle by increasing cyclic AMP production via adenylate cyclase activation.
| Metabolism | Metabolized by conjugation (sulfation) in the liver and possibly in the gut wall; undergoes extensive first-pass metabolism. |
| Excretion | Renal (25% unchanged, 75% as inactive sulfate conjugates), biliary/fecal (minimal) |
| Half-life | 3.8 hours (terminal elimination half-life; clinical context: dosing interval typically every 4-6 hours) |
| Protein binding | 50-60% (primarily to albumin) |
| Volume of Distribution | 2.5 L/kg (indicating extensive tissue distribution) |
| Bioavailability | Inhalation: 10-20% (dependent on device and technique); oral: low due to first-pass metabolism |
| Onset of Action | Inhalation: 5-15 minutes |
| Duration of Action | 3-6 hours (bronchodilation; may be shorter in severe asthma) |
2 inhalations (370 mcg each) by oral inhalation 4 times daily as needed; maximum 12 inhalations per day.
| Dosage form | AEROSOL, METERED |
| Renal impairment | No dose adjustment required for renal impairment; drug is not renally eliminated. |
| Liver impairment | No dose adjustment required for hepatic impairment; drug is hepatically metabolized but no child-pugh based guidelines exist. |
| Pediatric use | Not recommended for children under 12 years; for children 12 years and older, same as adult dose. |
| Geriatric use | No specific dose adjustment, but use with caution due to increased risk of tremors and tachycardia. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for BRETHAIRE (BRETHAIRE).
| Breastfeeding | Terbutaline is excreted into human milk in small amounts. The relative infant dose (RID) is estimated to be <10% of the maternal weight-adjusted dose. M/P ratio is approximately 1.8. Use with caution in breastfeeding women, especially in preterm infants due to potential for systemic effects such as tachycardia. Monitor infant for irritability and feeding difficulties. |
| Teratogenic Risk | FDA Pregnancy Category C. In animal studies, terbutaline (the active ingredient in BRETHAIRE) has been shown to be teratogenic at high doses, causing fetal skeletal abnormalities and delayed ossification. In humans, data are limited; however, no increased risk of congenital anomalies has been consistently demonstrated. Use during pregnancy only if the potential benefit justifies the potential risk to the fetus. First trimester: avoid unless necessary. Second and third trimesters: may be used for tocolysis, but associated with maternal tachycardia, pulmonary edema, and fetal hyperglycemia. |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to terbutaline or any component of the formulation"]
| Precautions | ["Paradoxical bronchospasm","Cardiovascular effects (increased heart rate, blood pressure, QT prolongation)","Hypokalemia","Immediate hypersensitivity reactions"] |
| Food/Dietary | No specific food interactions. Avoid excessive caffeine intake as it may increase the risk of nervousness, tremor, and palpitations. |
| Clinical Pearls | BRETHAIRE (terbutaline) is a beta-2 adrenergic agonist used as a bronchodilator. It should not be used as a first-line agent for acute asthma exacerbations due to potential cardiac effects. Use with caution in patients with hyperthyroidism, diabetes, or seizure disorders. Tolerance may develop with prolonged use. Monitor serum potassium levels as hypokalemia can occur. |
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| Fetal Monitoring | Monitor maternal heart rate, blood pressure, and serum potassium (terbutaline can cause hypokalemia). In pregnancy, monitor for signs of pulmonary edema (dyspnea, crackles), especially when used for tocolysis. Fetal monitoring: continuous fetal heart rate monitoring during tocolysis to detect tachycardia or distress. Assess fetal growth if used long-term. |
| Fertility Effects | No specific human data on terbutaline effects on fertility. Animal studies have not revealed impaired fertility. However, because terbutaline is a beta-2 adrenergic agonist, it may theoretically affect myometrial function and ovulation, but no significant adverse effects on fertility have been reported. |
| Patient Advice | Do not exceed prescribed dose; overuse can lead to serious side effects including chest pain and irregular heartbeat. · If your usual dose becomes less effective or you need more doses than usual, seek immediate medical attention as it may indicate worsening asthma. · Avoid getting the medication in your eyes; if this happens, rinse with water. · Shake the inhaler well before each use and prime it if new or not used for several days. · Keep track of the number of doses used; discard after the labeled number of doses even if it still sprays. |