Digitalis drug is used in the treatment of Congestive cardiac failure, Left ventricular failure, Arterial fibrillation and flutter, premature beats and Supra-ventricular tachycardia.

Dose of Digitalis Drugs

1. Rapid
   1. Digoxin 1.5 mg : initially 0.5 mg 6 hrly till digitalization
   2. Digoxin 0.4 mg : orally0.2 mg.6 hrly till digitalization
   3. Ouabain : I.V. ultra-short acting
2. Slow
   1. Digoxin 0.25 - 0.5 mg : initially 0.25 mg/day till digitalization.
   2. Digitoxin 0.2 mg : initially 0.2 mg. 8 hrly till digitalization.
3. Maintenance dose
   1. Digoxin 0.25 mg/day : 10-20 μgm/kg body wt
   2. Digitoxin 0.1-0.2 mg/d

Action of Digitalis

• It increases the force of Systolic contraction and decreases the oxygen expenditure for a given work output.
• Heart rate is decreased.
• Conduction through the A.V. node and Purkinje's fibers is depressed.
• Refractory period of atria and ventricles is decreased and that of AV node is increased (QT interval shortens). It acts by inhibiting the sodium-potassium ATPase. This causes faster release of calcium which enhances the automaticity, contractibility ectopic pacemaker activity.
• It is a cardiac glycoside. It works by correcting irregular heartbeat to a normal rhythm and increases the force with which the heart muscle contracts with every heartbeat.

Common side effects of Digitalis

• Cardiac: Premature beats atrial and ventricular tachycardia and fibrillation. Heart blocks, sinus bradycardia, Arrhythmia (irregular heartbeats)
• Gastrointestinal: Anorexia, nausea, vomiting (of central origin} and diarrhea.
• Neurological: Vertigo, Visual hallucinations, color vision defects and blurring, Headache, Neuralgic pains.
• Miscellaneous: Skin rashes (Eosinophilia), Dizziness, Gynecomastia, Premature labour with ECG changes in fetus and Visual impairment

Contra-indications of Digitalis

• High output states
• Partial heart (AV) block
• Ventricular tachycardia
• Constrictive pericarditis
• Myocarditis/Diphtheria
• Hypersensitivity
• WPW syndrome
• Hypokalemia