Cardiac Drugs Flashcards
MoA of furosemide
Inhibition of the Na/K/Cl co-transporter in the thick ascending loop of henle, resulting in decreased sodium and chloride reabsorption
What is furosemide used for in horses?
Exercise Induced Pulmonary Hemorrhage
ADEs of furosemide
- Acute administration may lead to dehydration, acute intravascular volume reduction
- May precipitate acute renal failure
- Electrolyte abnormalities (hyponatremia, hypokalemia, hypochloremia, hypocalcemia, hypomagnesemia)
What kind of medication is spironolactone? MoA?
Potassium-sparing diuretic
Competitive antagonism of aldosterone
What disease can spironolactone be used for in cats?
Primary aldosteronism
Clinical use of spironolactone in dogs
- Management of refractory edema
- Adjunct treatment of heart failure
Briefly discuss RAAS
- Renin (produced by kidneys) metabolizes angiotensinogen to angiotensin I
- Angiotensin I converted to II by ACE
- Angiotensin II potent vasoconstrictor and stimulates release of aldosterone
- Aldosterone causes Na retention
MoA of ACEIs
Inhibit ACE, therefore blocking conversion of angiotensin I to II, preventing vasoconstriction and reduce Na and water retention
What two ACEIs are commonly used in veterinary medicine?
Benazepril
Enalapril
Clinical use of ACEIs
Treatment of CHF
Systemic hypertension
PLN
MoA of amlodipine
Calcium channel blocker
What species is amlodipine most commonly used?
Cats
MoA of sildenafil
Phosphodiesterase inhibitor (PDE5)
Fun fact about sildenafil
Viagra! PDE5 found in lungs and corpus cavernosum
What is sildenafil used for?
Pulmonary hypertension
What does digoxin do to heart rate and contractility?
Decreases HR and improves contractility
Due to digoxin’s narrow therapeutic index, it has been replaced by…
Pimobendan
What arrhythmias can digoxin treat?
Supraventricular - atrial fibrillation/flutter
MoA of Pimobendan
Calcium sensitizes - positive inotrope
PDE3 inhibition - vasodilator
Clinical use of pimobendan
Treatment of CHF secondary to MVD, DCM in dogs
Treatment of CHF with LV systolic dysfunction - DCM, HCM
What receptors does epinephrine act on?
Mixed adrenergic agonist
B1, B2, and A1
Effects of epinephrine on B1
Positive inotrope
Positive chronotrope
Effects of epinephrine on B2
Bronchodilation and increased oxygenation
Effects of epinephrine on A1
Vasoconstriction
T/F: Effects of dopamine are dose-dependent
True - work on different receptors at different dosages
@ 2-5ug/kg/min, 5-10ug/kg/min, >10ug/kg/min what receptors does dopamine act on?
- Dopaminergic: Renal vasodilation
- B1: positive inotrope and increased cardiac output
- A1: pressor effects
What receptors does Dobutamine work on?
DoBBButamine - B1
Explain how vasopressin acts on BP
Vasopressin - ADH (antidiuretic hormone)
Water retention
Five classes of antiarrhythmic drugs
I. Sodium Channel Blockers
II. Beta blockers
III. Potassium Channel Blockers
IV. Calcium Chanel Blockers
V. Other
“Some Big Puppies Can’t Oxygenate”
Name the two main sodium channel blockers used
Quinidine
Lidocaine
Toxic doses of lidocaine
8mg/kg cows, sheep, goats
4mg/kg dogs
2mg/kg cats and horses
ADE of lidocaine
CNS excitation, muscle tremors, ataxia, vomiting
What do beta adrenergic antagonists do?
Decrease rate of AV conduction
Clinical indications of beta-blockers
Sinus tachycardia
Ventricular and supraventricular arrhythmias
Chronic hypertension
Pheochromocytoma
Decreased AH production in glaucoma
Is propranolol selective or non-selective? When is this drug contraindicated?
Non-selective
Blocks both B1 and 2
Avoid in patients with primary respiratory disease (bronchoconstriction)
Why is atenolol preferred over propranolol?
Atenolol is B1-selective and propranolol is non-selective, so you have less bronchospasm
ADEs of B blockers
Bradyarrhythmias
Hypotension
Heart failure - decompensation and worsening of CHF
Sotalol and amiodarone are __________________
Potassium channel blockers
