Digoksyn

Digoksyn is a cardiac glycoside used to treat heart failure and certain supraventricular arrhythmias. It is the same active drug as digoxin, a digitalis glycoside with a narrow therapeutic index. The primary mechanism is inhibition of the Na+/K+-ATPase pump in cardiac cells, increasing intracellular calcium and producing a positive inotropic effect. Digoksyn also increases vagal tone, slowing AV nodal conduction to help control ventricular rate in atrial fibrillation or flutter.

Pharmacokinetics: It can be given orally or intravenously. Oral bioavailability is variable but generally around 60–80%. The drug distributes widely and has a long half-life, roughly 1.5–2 days in individuals with normal renal function. It is predominantly cleared by the kidneys; dosing must be adjusted for renal impairment.

Indications: Used mainly to improve symptoms in heart failure with reduced ejection fraction and to control heart rate in atrial fibrillation or flutter with rapid response. It is not a first-line therapy for most acute or decompensated settings and is used selectively when symptom control remains.

Dosing and monitoring: Maintenance doses commonly range 0.125–0.25 mg daily, with lower or less frequent dosing in older patients or those with kidney disease. Serum digoxin concentrations are monitored; targets vary by condition (often 0.5–2.0 ng/mL, with some guidelines aiming lower for heart failure).

Toxicity and safety: Digoksyn has a narrow therapeutic index. Toxicity can involve GI symptoms, visual or CNS changes, and life-threatening arrhythmias. Risk factors include hypokalemia, renal impairment, and interacting drugs (amiodarone, verapamil, macrolide antibiotics). Severe toxicity may require digoxin-specific antibody fragments.