Which cardiac glycoside from purple foxglove is used for heart conditions?

• A. Atropine sulfate
• B. Digoxin
• C. Calcium chloride
• D. Magnesium sulfate

Answer: (B)

Digoxin is the cardiac glycoside derived from purple foxglove used for certain heart conditions because it provides both stronger heart muscle contraction and better heart rate control. By inhibiting the Na+/K+-ATPase pump in heart cells, it increases intracellular calcium via the Na+/Ca2+ exchanger, which boosts the strength of each heartbeat (positive inotropy). At the same time, it enhances vagal (parasympathetic) tone and slows conduction through the atrioventricular node, helping to control ventricular rate in conditions like atrial fibrillation.

Because of its narrow therapeutic window, careful dosing and monitoring are essential, including watching for signs of toxicity and considering kidney function and potential drug interactions.

The other options are not cardiac glycosides from foxglove and serve different roles: an anticholinergic used to raise heart rate, and electrolytes used for electrolyte disturbances or specific arrhythmias, not for increasing contractility or AV nodal slowing.