特布他林
特布他林是一種合成的選擇性 **β2-腎上腺素受體激動劑**，在獸醫學中主要作為支氣管擴張劑使用。它常用於輔助治療心肺疾病，如 **貓氣喘、犬慢性支氣管炎、氣管塌陷和肺水腫**。 除了呼吸道應用外，特布他林偶爾也會被標籤外使用作為 **安胎藥**（透過放鬆子宮平滑肌來抑制早產），以及用於治療某些 **心跳過緩**。在馬医學中，它可透過皮內注射作為診斷工具，用於定量測試無汗症。 > **臨床提示：** 雖然在標準劑量下對 β2 受體具有高度選擇性，但較高劑量可能會影響 β1 受體，導致直接的心臟刺激。周邊行管擴張引發的反射性心跳過速也是常見的臨床觀察。
作用機制: Terbutaline selectively binds to and stimulates **beta-2 adrenergic receptors** located predominantly in bronchial, vascular, and uterine smooth muscle. **Mechanism Pathway:** Beta-2 receptor activation → Stimulation of **adenylyl cyclase** → Increased intracellular **cyclic AMP (cAMP)** → Activation of **protein kinase A (PKA)** → Decreased intracellular calcium concentrations → **Smooth muscle relaxation**. This results in significant bronchodilation and reduced airway resistance. At therapeutic doses, it has minimal affinity for **beta-1 receptors** (cardiac muscle) and virtually no **alpha-adrenergic** activity.
各物種劑量
- For acute exacerbations of feline asthma treated at home · 0.01 mg/kg SC or IM · SC/IM · PRN · Beneficial response occurs in 15-30 minutes. A heart rate approaching 240 BPM indicates absorption.
- For feline asthma · 0.312-0.625 mg (total dose) per cat PO two to three times daily · PO · q8-12h · May adjust dose up to 1.25 mg in larger cats if needed
- For bradyarrhythmias · 0.625 mg PO q8-12h · PO · q8-12h · Improvement usually partial and often temporary
- For acute bronchoconstriction (initial crisis) · 0.01 mg/kg IV, SC, IM · IV/SC/IM · Single dose
- For use as a quantitative intradermal terbutaline sweat test (QITST) to identify anhidrosis · Eight 0.1 mL intradermal injections of serial 10-fold dilutions of terbutaline sulfate in 0.9% saline (0.001, 0.01, 0.1, 1, 10, 100 and 1000 mg/L) · Intradermal · Single dose · ARCI UCGFS Class 3 Drug
- General bronchodilation · 0.0033 mg/kg IV · IV · Not specified · ARCI UCGFS Class 3 Drug
- For a trial to treat intrathoracic tracheal collapse, expiratory cough or dyspnea and marked exercise intolerance · 1.25-5 mg (total dose) PO two to three times daily · PO · q8-12h
- As a bronchodilator in chronic bronchitis · Small dogs: 0.625-1.25 mg (total dose) PO q12h; medium-sized dogs: 1.25-2.5 mg (total dose) PO q12h; large dogs: 2.5-5 mg PO q12h · PO · q12h
劑量為持牌獸醫專業人員的臨床參考。請務必對照最新藥品說明書及個別病患確認。
給藥途徑
禁忌症
- Known hypersensitivity to terbutaline
- Heart disease (especially congestive heart failure or cardiomyopathy)
- Known hypersensitivity to terbutaline or sympathomimetic amines
- Severe cardiac arrhythmias
- Hypertrophic cardiomyopathy (relative contraindication)
不良反應
- Increased heart rate (tachycardia)
- Tremors
- CNS excitement (nervousness)
- Dizziness
- Sweating (reported in horses after parenteral injection)
- Transient hypokalemia
- Tachycardia
- Muscle tremors
- Restlessness or excitement
- Hypokalemia (with high doses or prolonged use)
- Hypertension or hypotension
藥物相互作用
- Inhalation Anesthetics (e.g., halothane, isoflurane, methoxyflurane) · May predispose the patient to ventricular arrhythmias, particularly with preexisting cardiac disease; use cautiously.
- Beta-Adrenergic Blocking Agents (e.g., propranolol) · May antagonize the bronchodilating and cardiovascular actions of terbutaline.
- Digoxin · Concurrent use with digitalis glycosides may increase the risk of cardiac arrhythmias. · moderate
- Monoamine Oxidase Inhibitors (MAOIs) · May potentiate the vascular effects of terbutaline.
- Other Sympathomimetics · May increase the risk of developing adverse cardiovascular effects.
- Tricyclic Antidepressants · May potentiate the vascular effects of terbutaline.
- Beta-blockers (e.g., propranolol) · Antagonize the bronchodilating effects of terbutaline · major
- Sympathomimetics · Additive cardiovascular toxicity and CNS stimulation · moderate
- Inhalant anesthetics (e.g., halothane) · Sensitize the myocardium, increasing the risk of severe arrhythmias · major
- Tricyclic antidepressants (TCAs) / MAOIs · May potentiate vascular effects · moderate
監測
- Clinical symptom improvement (respiratory rate/effort)
- Auscultation of lung sounds
- Cardiac rate and rhythm (especially if indicated for arrhythmias or if tachycardia develops)
- Serum potassium (early in therapy if the animal is susceptible to hypokalemia)
- Heart rate and rhythm
- Respiratory rate and effort
- Serum potassium levels (with prolonged or high-dose therapy)
過量
Clinical signs of significant systemic overdose may include **arrhythmias** (bradycardia, tachycardia, heart block, extrasystoles), **hypertension, fever, vomiting, mydriasis, and CNS stimulation**. **Treatment:** - For recent oral ingestion without significant cardiac/CNS effects: Empty gut, administer activated charcoal, and a cathartic. - For severe cardiac arrhythmias: A beta-blocking agent (e.g., propranolol) can be used, but **caution is advised** as it may precipitate severe bronchoconstriction.
VetSheet 藥物參考供持牌獸醫專業人員作臨床決策輔助之用,不能取代專業判斷或廠方最新藥品說明書。