Which drug increases contractility (inotropic)?

Which drug increases contractility (inotropic)?

• A. Digitalis
• B. Digoxin
• C. Levosimendan
• D. Atropine

Answer: (C)

Inotropic means increasing the force of the heart’s contraction. Levosimendan does this by a distinct mechanism: it sensitizes the cardiac myofilaments to calcium, binding to troponin C and enhancing the contractile response when calcium is present. This boosts the strength of contraction without a large rise in intracellular calcium, which can reduce the risk of increased myocardial oxygen demand and arrhythmias. Additionally, levosimendan opens potassium channels in vascular smooth muscle, causing vasodilation, so it acts as an inodilator and provides both stronger contraction and reduced afterload. Digitalis and digoxin also raise contractility, but they do so by inhibiting the Na+/K+ ATPase, which increases intracellular calcium. This approach carries a narrower therapeutic window and other drawbacks, making levosimendan the more targeted choice for increasing contractility in this context. Atropine, on the other hand, mainly increases heart rate by blocking parasympathetic activity and does not enhance contractility.

Inotropic means increasing the force of the heart’s contraction. Levosimendan does this by a distinct mechanism: it sensitizes the cardiac myofilaments to calcium, binding to troponin C and enhancing the contractile response when calcium is present. This boosts the strength of contraction without a large rise in intracellular calcium, which can reduce the risk of increased myocardial oxygen demand and arrhythmias. Additionally, levosimendan opens potassium channels in vascular smooth muscle, causing vasodilation, so it acts as an inodilator and provides both stronger contraction and reduced afterload.

Digitalis and digoxin also raise contractility, but they do so by inhibiting the Na+/K+ ATPase, which increases intracellular calcium. This approach carries a narrower therapeutic window and other drawbacks, making levosimendan the more targeted choice for increasing contractility in this context. Atropine, on the other hand, mainly increases heart rate by blocking parasympathetic activity and does not enhance contractility.