Inotropes Drugs Flashcards
Describe the mechanism of action of pimobendane
Pimobendane = inodilator (positive inotrope and vasodilator)
Acts as a calcium sensitizer and PDE-III inhibitor
Calcium sensitizer : increase affinity of calcium for troponin C
PDE-III inhibition : inhibit breakdown of cAMP —> leads to vasodilation
Other : anti-platelet activity (fairly minimal)
What are the indications for pimobendan use ?
Asymptomatic DCM dogs —> Protect study.
Chronic degenerative valve disease if systolic dysfunction (before failure) —> EPIC study
Congestive heart failure secondary to chronic degenerative mitral valve disease or DCM —> Quest study (pimo vs benazepril)
Restrictive cardio myopathy in cats
What are the main side effects of pimobendan
Can potentiate arrhythmias
Describe the mechanism of action of dobutamine
Synthetic catecholamine
Action : B1 > B2/a1 agonist.
Increase Ca L-type channel opening and calcium influx.
What are the indication for the use of dobutamine
Cardiogenic shock —> hypotension secondary to low cardiac output.
Better with DCM than MVD
Short term IV inotropic in support for CHF.
What are the side effects associated with dobutamine
Mild vasoconstriction (more at higher doses). At higher doses can also causes tachycardia and arrhythmia
Causes less tachycardia and vasoconstriction compared to dopamine.
Describe the mechanism of action of digoxin
Class = digitalis glycoside.
Increases the force of myofiber shortening by increasing the cytosolic calcium —> inhibits Na-K ATPase pump —> increases Na/Ca exchange —> increases intracellular calcium
Also anti-arrhythmic effect : lengthens the phases 4 and 0 of the action potential (in the AV node)
What are the indications for digoxin
Atrial fibrillation
Other SVT.
**only positive inotrope that slows the heart rate **
What are the possible side effects of digoxin
Principal side effect : GI (vomiting, diarrhea and anorexia)
Narrow therapeutic window
Increased risk of toxicity with hypokaliemia.
Can also be arrhythmogenic.
