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# Bricanyl (Terbutaline)
## Overview
Terbutaline is a selective beta-2 adrenergic agonist. It acts as a bronchodilator by stimulating adenyl cyclase, increasing cyclic AMP, and relaxing bronchial smooth muscle. While historically used for preterm labor (tocolysis), this use is now largely discouraged by regulatory bodies due to significant maternal cardiovascular risks.
## Primary Indications
* Acute bronchospasm (asthma, COPD).
* *Note: Off-label use for tocolysis exists but is associated with serious maternal/fetal adverse effects and is not recommended by the FDA.*
## Adult Dosing
* **Subcutaneous (SQ):** 0.25 mg injected into the lateral deltoid area. May repeat once after 15–30 minutes if necessary. Do not exceed 0.5 mg in a 4-hour period.
* **Oral (PO):** 2.5–5 mg every 6–8 hours. Maximum 15 mg daily.
## Pediatric Dosing
* **Ages 12+:** Use adult dosing.
* **Ages < 12:** 0.01 mg/kg/dose SQ; maximum single dose 0.25 mg. May repeat every 15–30 minutes for up to 3 doses.
* *Note: Pediatric oral dosing is rarely used and varies by local institutional protocol.*
## Dose Adjustments
* **Renal Impairment:** Use with caution; reduce dose or increase dosing interval in patients with severe renal impairment as the drug is renally excreted.
* **Hepatic Impairment:** No specific guidelines; use caution.
## Contraindications
* Known hypersensitivity to terbutaline or any component of the formulation.
* **Tocolysis:** Prolonged administration beyond 48–72 hours is contraindicated due to risk of maternal pulmonary edema and cardiac events.
## Adverse Effects
* **Common:** Tachycardia, palpitations, tremors (particularly hand tremor), nervousness, dizziness, headache.
* **Serious:** Myocardial ischemia, arrhythmias (atrial fibrillation, SVT), hypokalemia, hyperglycemia, and pulmonary edema (especially in pregnant patients).
## Key Drug Interactions
* **Beta-blockers:** Antagonize the bronchodilating effects of terbutaline; avoid concurrent use.
* **Potassium-depleting agents (e.g., diuretics, corticosteroids):** May worsen the hypokalemic effect of terbutaline.
* **MAO Inhibitors/Tricyclic Antidepressants:** May potentiate the cardiovascular effects of terbutaline.
## Monitoring
* **Cardiac:** Monitor heart rate, rhythm (ECG if symptomatic), and blood pressure.
* **Metabolic:** Monitor serum potassium and glucose levels in patients receiving frequent or high-dose therapy.
* **Respiratory:** Monitor pulmonary function/breath sounds for improvement in bronchospasm.
## Clinical Pearls
* **Subcutaneous Administration:** Always use the smallest volume possible. The 0.25 mg SQ dose is preferred for rapid relief of acute bronchospasm.
* **Tolerance:** Prolonged, regular use can lead to tachyphylaxis (diminished effect over time).
* **Safety Warning:** Terbutaline has a boxed warning regarding the use of oral formulations for prevention of preterm labor; its use for this indication is considered unsafe by the FDA.
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**Educational Disclaimer:** This information is for educational purposes only. Always consult current institutional protocols, prescribing information (package inserts), and clinical decision support tools (e.g., UpToDate, Lexicomp) before prescribing or administering medication.
