Digoksiini

Digoksiini, or digoxin in English, is a cardiac glycoside used in the treatment of certain heart conditions. It is historically derived from foxglove plants (Digitalis) and has been employed in medicine for centuries. In Finnish and several other languages, the drug is referred to as digoksiini.

Mechanism of action and effects

Digoksiini inhibits the Na+/K+-ATPase pump in cardiac myocytes, increasing intracellular sodium and reducing the extrusion of calcium via the Na+/Ca2+ exchanger. The result is a positive inotropic effect, meaning stronger heart muscle contractions. Digoksiini also enhances vagal (parasympathetic) tone, which slows conduction through the atrioventricular (AV) node and can help control heart rate in certain rhythm disorders.

Clinical uses

Digoksiini is used to improve symptoms and exercise tolerance in chronic heart failure with reduced ejection fraction. It is also used for rate control in atrial fibrillation or atrial flutter when rapid ventricular response is a concern, particularly in patients who remain symptomatic despite other therapies.

Pharmacokinetics and monitoring

The drug can be given orally or intravenously. It has variable bioavailability and a large volume of distribution, with a long half-life (roughly 36–48 hours in individuals with normal renal function). Digoksiini is primarily excreted by the kidneys, so dosing must be adjusted for renal impairment. Serum digoxin concentrations are monitored to stay within a therapeutic range (commonly about 0.5–2.0 ng/mL, with some recommendations recommending lower targets for atrial fibrillation).

Toxicity and interactions

Digoxin has a narrow therapeutic window. Toxicity can cause gastrointestinal symptoms, confusion, visual disturbances, and potentially dangerous cardiac arrhythmias. Risk factors include renal impairment and electrolyte disturbances (notably hypokalemia). Management may require dose adjustment, withdrawal, or administration of digoxin-specific antibody fragments in severe cases. Interactions with other drugs (eg, amiodarone, verapamil, diltiazem, quinidine, certain diuretics) can raise digoxin levels or increase toxicity.

History and context

Digoksiini/digoxin remains a classic therapy with a well-established, though narrow, safety margin, used when indicated and monitored carefully.