멕실레틴

항부정맥제 (Class IB)

멕실레틴은 리도카인과 매우 유사한 전기생리학적 특성을 지닌 경구용 **Class IB 항부정맥제**입니다. 리도카인은 초회통과대사가 커서 경구 투여가 불가능하기 때문에, 멕실레틴은 부정맥의 만성 관리를 위한 "경구용 리도카인"으로 자주 간주됩니다. 수의학에서는 주로 개에서 **심실성 부정맥**(심실조기수축[PVC] 및 심실성 빈맥 등)을 치료하는 데 사용됩니다. 특히 부정맥유발성 우심실 심근병증(ARVC)이 있는 복서견이나 확장성 심근병증(DCM)이 있는 도베르만 핀셔에게 자주 사용됩니다. 시너지 효과를 위해 베타차단제(예: 아테놀롤)나 소탈롤과 자주 병용됩니다. 또한 멕실레틴은 **선천성 근강직증**(차우차우 및 미니어처 슈나우저에서 발생) 및 **근파동증**(잭 러셀 테리어에서 발생)과 같은 특정 희귀 유전성 근육 질환을 치료하는 데에도 사용됩니다.

작용 기전: Mexiletine is a **Class IB antiarrhythmic**. * **Mechanism**: It binds to and inhibits the inward **fast sodium channels (Na+)** in the myocardial cell membrane. * **Electrophysiologic Effects**: By blocking these channels, it reduces the rate of rise of the action potential (**Phase 0**). In Purkinje fibers, it decreases automaticity, shortens the action potential duration, and decreases the effective refractory period. * **Selectivity**: Like lidocaine, it is highly selective for diseased, ischemic, or rapidly firing myocardial tissue, making it effective at suppressing ventricular ectopic pacemakers without significantly depressing normal sinus node function or conduction (unless pre-existing abnormalities exist).

동물 종별 용량

Dogs

Treating or assisting in treatment of ventricular arrhythmias · 5-8 mg/kg · PO · q8h
Treating or assisting in treatment of ventricular arrhythmias · 4-10 mg/kg · PO · q8h
Ventricular arrhythmias in Boxers · 5-7.5 mg/kg · PO · three times daily · Given with sotalol at 1.5-3 mg/kg twice daily; was successful in 7/8 dogs treated in study.
Treating or assisting in treatment of ventricular arrhythmias · 4-8 mg/kg · PO · q8h · Combined with atenolol (0.5 mg/kg PO q12-24h).
Familial arrhythmic cardiomyopathy of Boxers (ARVC) · 5-8 mg/kg · PO · q8h · Given with atenolol at 12.5 mg (total dose) q12h.
Treating or assisting in treatment of ventricular arrhythmias · 5-6 mg/kg · PO · q8h · Always give with food to avoid nausea.
Myotonia congenita or myokymia · 8.3 mg/kg · PO · q8h · Most studied in Chow Chows, miniature schnauzers, and Jack Russell terriers.

용량은 면허 수의 전문가를 위한 임상 참고 자료입니다. 항상 최신 라벨과 개별 환자에 대해 확인하십시오.

투여 경로

금기

Pre-existing 2nd or 3rd degree AV block (without a pacemaker)
Cardiogenic shock
Known hypersensitivity to mexiletine

이상반응

Vomiting (very common)
Nausea
Trembling/Tremors
Unsteadiness/Ataxia
Dizziness
Depression/Lethargy
Shortness of breath
Proarrhythmia (PVCs)
Chest pain
Seizures (rare)
Agranulocytosis (rare)
Thrombocytopenia (rare)

약물 상호작용

Antacids (Aluminum-Magnesium) · May slow the absorption of mexiletine.
Atropine · May reduce the rate of oral absorption.
Cimetidine · May increase or decrease mexiletine blood levels.
Griseofulvin · May accelerate the metabolism of mexiletine.
Lidocaine · May cause additive adverse effects (especially CNS toxicity).
Metoclopramide · May accelerate the absorption of mexiletine.
Opiates · May slow the absorption of mexiletine.
Phenobarbital · May accelerate the metabolism of mexiletine.
Primidone · May accelerate the metabolism of mexiletine.
Phenytoin · May accelerate the metabolism of mexiletine.
Rifampin · May accelerate the metabolism of mexiletine.
Theophylline · Mexiletine may reduce the metabolism of theophylline, potentially leading to theophylline toxicity.
Urinary Acidifying Drugs (e.g., methionine, ammonium chloride) · May accelerate the renal excretion of mexiletine.

모니터링

Electrocardiogram (ECG) to assess antiarrhythmic efficacy and monitor for proarrhythmia
Clinical signs of adverse effects (especially GI and CNS signs)
Plasma concentrations (Therapeutic range in humans: 0.5-2 mcg/mL; note that toxicity may be noted even at therapeutic levels)
Liver enzymes (AST may transiently increase in a small percentage of patients)

과용량

Toxicity associated with overdosage can be significant and life-threatening. * **Clinical Signs**: In human case reports, **CNS signs (tremors, seizures, depression) always preceded cardiovascular signs** (hypotension, bradycardia, heart block). * **Treatment**: * Perform GI tract emptying protocols (emesis/gastric lavage) if indicated and safe. * Administer supportive therapy. * Acidification of the urine may be considered to enhance urinary excretion. * **Atropine** may be useful if severe hypotension or bradycardia occurs.

VetSheet 약물 레퍼런스는 면허 수의 전문가를 위한 임상 의사결정 보조 도구이며, 전문적 판단이나 제조사의 최신 라벨을 대신하지 않습니다.