索他洛爾
索他洛爾 (Sotalol) 是一種獨特的抗心律不整藥物，兼具**非選擇性 β-受體阻斷劑 (第二類)** 與 **鉀離子通道阻斷劑 (第三類)** 的特性。 * **臨床用途**：在獸醫學中，主要用於治療犬貓的心室性心搏過速 (Ventricular tachycardia)，偶爾用於心房上性心搏過速。 * **目標族群**：特別常被用於治療**拳師犬**的心室性心律不整（通常與致心律不整性右心室心肌病 ARVC 相關），以及對利多卡因 (Lidocaine) 產生抗藥性的病例。 * **藥理特點**：索他洛爾是一種消旋混合物。其 *d-* 和 *l-* 異構物均具有第三類抗心律不整活性，但只有 *l-* 異構物具有 β-阻斷活性。其 β-阻斷效力約為普萘洛爾 (Propranolol) 的 30%。
作用機制: Sotalol exerts a dual mechanism of action: * **Class II (Beta-Blocking) Action**: Competitively antagonizes **non-selective $\beta_1$ and $\beta_2$ adrenergic receptors** $\rightarrow$ decreases heart rate, slows AV nodal conduction, and exerts a negative inotropic effect on the myocardium. * **Class III (Antiarrhythmic) Action**: Selectively inhibits the **rapid delayed rectifier potassium current ($I_{Kr}$)** $\rightarrow$ prolongs the action potential duration (APD) and the effective refractory period (ERP) in both atrial and ventricular myocardium without affecting depolarization or conduction velocity.
各物種劑量
- General antiarrhythmic · 2 mg/kg · PO · twice daily
- For ventricular tachyarrhythmias · 2 mg/kg · PO · q12h
- General antiarrhythmic · 1-2 mg/kg · PO · q12h
- General antiarrhythmic · 1/8th of an 80 mg tablet (approximately 2 mg/kg) · PO · twice daily
- Ventricular arrhythmias · 10-20 mg/cat · PO · q12h · Ongoing
- General antiarrhythmic · 1-2 mg/kg · PO · q12h
- General antiarrhythmic · 1-3 mg/kg · PO · twice daily
- For ventricular tachycardia · 1-2 mg/kg · PO · twice daily
- For ventricular tachyarrhythmias in Boxers in combination with mexiletine · 1.5-3 mg/kg · PO · twice daily · Given with mexiletine (5-7.5 mg/kg PO three times daily)
- In Boxers · 40-80 mg (total dose) · PO · q12h
- Ventricular arrhythmias · 0.5-3 mg/kg · PO · q12h · Ongoing · Start with lower doses if myocardial function is reduced.
- Ventricular arrhythmias (Acute/Severe) · 0.5 mg/kg given over 2 min, up to 3 times (to a total dose of 1.5 mg/kg) · IV · As needed · Acute setting · Anecdotal dosing.
給藥途徑
禁忌症
- Asthma or reactive airway disease
- Sinus bradycardia
- 2nd or 3rd degree AV block (unless artificially paced)
- Long QT syndromes
- Cardiogenic shock
- Uncontrolled congestive heart failure (CHF)
- Asthma
- Atrioventricular (AV) block
- Decompensated congestive heart failure (CHF)
- Long QT interval on ECG
不良反應
- Negative inotropism (decreased heart contractility)
- Proarrhythmia (can induce new or worsen existing arrhythmias)
- Dyspnea / Bronchospasm
- Fatigue / Lethargy
- Dizziness / Syncope exacerbation
- Nausea / Vomiting
- Bradycardia
- Hypotension
- Bradyarrhythmias
- Bronchospasm
- Depression
- Nausea
- Vomiting
- Diarrhoea
- Decreased cardiac output
- Precipitation of congestive heart failure
- Prolonged QT interval
藥物相互作用
- Amiodarone · May prolong refractory periods; concurrent use not recommended.
- Anesthetics, General · Additive myocardial depression may occur.
- Antacids · May reduce oral sotalol absorption; separate doses by at least 2 hours.
- Antiarrhythmics, Class IA (quinidine, procainamide, disopyramide) · May prolong refractory periods and QT interval; concurrent use not recommended.
- Antiarrhythmics, Class IB/IC (lidocaine, mexiletine, phenytoin, flecainide) · May prolong QT interval.
- Calcium Channel Blockers (verapamil, diltiazem) · Potential to increase hypotensive effects; additive effects on AV conduction or ventricular function. Use with caution.
- Cisapride · May prolong QT interval.
- Clonidine · Increased risk for rebound hypertension if clonidine is discontinued after concomitant therapy.
- Digoxin · Potential for increased risks for proarrhythmic events.
- Erythromycin / Clarithromycin · May prolong QT interval.
- Lidocaine · Clearance of lidocaine may be impaired by sotalol.
- Phenothiazines · May prolong QT interval. · moderate
監測
- Efficacy via Electrocardiogram (ECG)
- Adverse effects (heart rate, blood pressure, respiratory effort)
- Renal function (baseline and periodic, as drug is renally excreted)
- Blood glucose (especially in diabetic patients)
- Heart rate and rhythm (Holter ECG monitoring is highly recommended to assess efficacy and detect proarrhythmias)
- Blood pressure
- Renal function (BUN, Creatinine, SDMA)
- Serum electrolytes (especially potassium, to avoid hypokalaemia)
- Clinical signs of congestive heart failure
過量
Overdoses may result in **bradycardia, hypotension, congestive heart failure, bronchospasm, and hypoglycemia**. * **Treatment**: Use gut evacuation (emesis or gastric lavage) if not contraindicated and when there is a significant risk of morbidity. * **Supportive Care**: Treat adverse effects symptomatically and supportively (e.g., atropine for bradycardia, fluids/vasopressors for hypotension, bronchodilators for bronchospasm).
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