Na⁺/K⁺-ATPase inhibitor
- ↑ intracellular sodium → ↓ Na⁺/Ca²⁺ exchange → ↑ intracellular calcium/inotropy
- Also slows AV conduction
- Hypokalemia increases target binding/toxicity
- Toxicity: nausea, yellow-green vision, arrhythmias
- Narrow therapeutic index
Drugs with this mechanism (1)
- Digoxin — Classic Na/K-ATPase inhibitor for heart failure and rate control; narrow index.
Self-check
- Why does Na⁺/K⁺-ATPase inhibition increase inotropy?
More intracellular sodium reduces Na⁺/Ca²⁺ exchange, raising intracellular calcium. - Which electrolyte abnormality increases Na⁺/K⁺-ATPase inhibitor binding and toxicity?
Hypokalemia.
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