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Pharm Ch19
Cardiac Contractility
Question | Answer |
---|---|
MOA of digoxin & digitoxin | Cardiac Glycosides (raise intracellular Ca2+ via inhibit SR Na+ pump) |
AV block (bradycardic), enhanced His-Purkinje conduction, narrow therapeutic window, large Vd, positive inotrope, 90% renal exc , Tx: A-fib, HF (improves functional status) | Digoxin |
K+ wasting diuretics (furosemide) decrease plasma K+, increases affinity for Na+ pump leading to this type of toxiciity | Digoxin |
Excreted by liver, can be used in kidney disease, very long half-life (7 days) | Digitoxin |
MOA of Dopamine, Dobutamine, Epinephrine, Norepinephrine, Isoproterenol | B-adrenergic Receptor Agonists (raise intracellular cAMP & Ca2+) |
Low dose: peripheral vasodilator Intermediate: widespread vasodilator, activates B1-R High dose: activates a1-R (vasoconstriction) Tx: sepsis, anaphylaxis, cardiogenic shock, HF, ADR: w/ MAOI can cause tachycardia, arrhythmia | Dopamine |
pure B1-agonist, short half-life, Sympathomimetic DOC for acute cardiogenic circulatory failure | Dobutamine |
nonselective, low dose: peripheral B2, high dose: a1-R (vasoconstriction), Tx: HF (IV), Inhaled: asthma SQ: anaphylaxis, ADR: high doses, can cause tachycardia, arrhythmia | Epinephrine |
B1, a1-agonist Tx: distributive shock (gram neg sepsis) but can cause tachycardia, arrhythmia | Norepinephrine |
selective B1 (high HR), some B2 can cause vasodilation & hypotension Tx: refractive bradycardia, B-antagonist overdose CI: active CAD | Isoproterenol |
MOA of Theophylline (nonspecific), Inamrinone, Milrinone | Phosphodiesterase (PDE) Inhibitors (raise intracellular cAMP & Ca2+) |
Selective PDE3 inhibitors, "inodilators" - positive inotrope, arterial & venous vasodilation; Tx: short-term support of failing circulation ADRs: Thrombocytopenia, increased mortality in HF | Inamrinone Milrinone |
MOA of Levosimendan | Calcium-sensitizing Agents (positive inotrope, inodilator) |