Which drug class exerts a positive inotropic effect on the heart, increasing the strength of contractions and slowing the heart rate?

Which drug class exerts a positive inotropic effect on the heart, increasing the strength of contractions and slowing the heart rate?

• A. Antiviral
• B. DMARDs
• C. Cardiac Glycoside
• D. Expectorant

Answer: (C)

Cardiac glycosides increase the force of heart contractions (positive inotropy) by inhibiting the Na+/K+ ATPase pump in cardiac cells. This raises intracellular sodium, which reduces the activity of the Na+/Ca2+ exchanger, allowing more calcium to remain inside the cell. The extra calcium boosts the strength of each contraction. At the same time, these drugs enhance vagal tone, especially at the AV node, which slows the heart rate. So the combination of stronger contractions with a slower heart rate fits this description. Digoxin is a classic example. Other options don’t produce this contractility boost or the linked bradycardia—antivirals fight infection, DMARDs modify immune responses, and expectorants affect mucus clearance.

Cardiac glycosides increase the force of heart contractions (positive inotropy) by inhibiting the Na+/K+ ATPase pump in cardiac cells. This raises intracellular sodium, which reduces the activity of the Na+/Ca2+ exchanger, allowing more calcium to remain inside the cell. The extra calcium boosts the strength of each contraction. At the same time, these drugs enhance vagal tone, especially at the AV node, which slows the heart rate. So the combination of stronger contractions with a slower heart rate fits this description. Digoxin is a classic example. Other options don’t produce this contractility boost or the linked bradycardia—antivirals fight infection, DMARDs modify immune responses, and expectorants affect mucus clearance.