VPT 311: General and Systemic Veterinary Pharmacology (2+1)

Adverse reactions of cardiac glycoside

ADVERSE REACTIONS OF CARDIAC GLYCOSIDES

• Risk of toxicity is greater in patients with advanced heart disease,in high dosage, renal disease, age and hypothyroidism.
• Factors that increase myocardial sensitivity to digitalis toxicity include myocardial disease or ischemia, hypokalemia, high serum calcium and low serum magnesium.
• Symptoms of toxicity can be grouped as cardiac symptoms and non-cardiac symptoms.
• Cardiac symptoms of toxicity
  • Sinus bradycardia,
  • S-A block,
  • A-V block, tachycardia,
  • premature ventricular contraction
• Non-cardiac symptoms of toxicity
• gastrointestinal disturbances like anorexia, nausea, vomiting fatigue and muscle weakness
• CNS effects like confusion, hallucination, restlessness, insomnia, drowsiness and occasionally overt psychoses
• Visual effects like hazy vision, difficulty in reading, photophobia, chromatopsia (yellow or green colour appearance)
• gynaecomastia (antiadrenergic effect).

TREATMENT OF CARDIAC GLYCOSIDE TOXICITY

• Withhold cardiac glycosides
• Withhold potassium depleting diuretics
• Administer potassium salts
• Administer antiarrhythmics if arrhythmias appear to be life threatening

Administer agents like activated charcoal to bind digoxin in the gastrointestinal tract.