ソタロール
ソタロール（Sotalol）は、**非選択的β遮断薬（クラスII）**および**カリウムチャネル遮断薬（クラスIII）**の両方の特性を併せ持つユニークな抗不整脈薬です。 * **臨床的有用性**：獣医療では主に犬や猫の心室頻拍の治療に使用され、場合によっては上室性頻拍にも使用されます。 * **対象動物**：特に**ボクサー犬**の心室性不整脈（不整脈源性右室心筋症：ARVCに関連することが多い）や、リドカイン不応性の症例の管理に好んで用いられます。 * **薬理学的特徴**：ソタロールはラセミ体です。*d-*体および*l-*体の両方がクラスIII抗不整脈作用を示しますが、β遮断作用を持つのは*l-*体のみです。そのβ遮断作用の強さはプロプラノロールの約30%です。
作用機序: 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.
動物種別の用量
- 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.
投与経路
禁忌
- 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
有害事象
- 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
薬物相互作用
- 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
モニタリング
- 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
過量投与
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).
VetSheet の薬剤リファレンスは、獣医療従事者向けの臨床意思決定支援を目的としており、専門的判断やメーカーの最新添付文書に代わるものではありません。