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Flashcards in E1. Cardiovascular drugs Deck (74):

What is the drug of choice for a complete AV block?



What is the drug of choice for an incomplete AV block?



What is the drug you want to use in an emergency with bradycardia?



List the categories of your cardiac stimulants. (4)
Say what each does.

Beta-1 agonists: positive inotropic agent that increase the strength of muscular contraction.
phosphodiesterase inhibitors: Increase contractility and decrease afterload in the heart.
glucagon: increase contractility
calcium sats: inc. contractility


What is your drug of choice to treat sinus bradycardia?



What are the two ways to treat congestive heart failure (CHF)?
(general, exact on either CATEGORY)

– non drug therapy (restricted salt diet and/or restricted exercise)
– drug therapy


List the types of drugs used in the treatment of congestive heart failure. (6)o

– positive inotropic drugs
– inodilators
– vasodilators
– diuretics
– beta blockers
– other agents


What are the two types of positive inotropic drugs?

Digitalis glycosides and beta-1 agonists


List the three digitalis glycosides.

• Digitoxin
• Digoxin
• Ouabain


What is the digoxin (and other digitalis glycosides) mechanism of action?

Inhibition of sodium, potassium ATPase in the myocardial cell membrane increases sodium available for exchange with calcium (increased contractility and heart)
*the result is increased in intracellular calcium which results in a positive inotropic effect*


What is the cardiovascular effects of digoxin? (5)

–Positive inotropic effect
– *reduction in sinus rate and slowing AV conduction*
– prolonged PR intervals in ECG
– increased mechanical efficiency of the failing hearts
– normalization of blood pressure and peripheral resistance


What are digoxin effects on the kidney and G.I. tract?

Kidney: diuretic effect mainly secondary to increased cardiac output.
G.I. tract: G.I. irritation, vomiting


What is digoxin pharmacokinetics?(6)
(adimin, bioavail., 1/2 life, metab, excretion)

– oral administration or IV in an emergency
– oral bioavailability is more for the elixir (75%) than for the (60%)
– the half-life depends on the species (average 24 hours (for dog, horse is less, cat is more))
– small amount is metabolized by the liver
– undergoes enterohepatic recycling
– excretion is mainly renal in dogs and horses, and the renal and hepatic in cats.


What is digoxin therapeutic use?

–Treat congestive heart failure
– treat atrial arrhythmias in dogs


What are the adverse effects of digoxin? (4)

– has narrow safety margin
– cats are more sensitive than dogs
– cardiac
– tachyarrhythmias


What are the predisposing factors for tachyarrhythmias involving digoxin? (7)p

» Hypokalemia
» Hypomagnesemia
» *Hypercalcemia*
» *Hypernatremia*
» *Hypothyroidism*
» *Hyperthyroidism*
» Hypoxemia

* read slides 16-18


Name the two drugs that are beta-1 agonists.

Dopamine and dobutamine.


Dopamine and dobutamine share what type of effect on the heart?

Positive inotropic effects


Say what dopamines effect is at low dose, medium dose, and high dose.

Low dose: vasodilation in visceral blood vessels (good for shock treatment, increasing RBF)
medium dose: increase cardiac automaticity
high dose: vasoconstriction to increase blood pressure

*dobutamine increases cardiac contractility, not perfusion.


List the three inodilator drugs.
Of the three which is the most important?

• Pimobendan
• Inamrinone
• Milrinone



What is Pimobendans classification?

An indicator drug (positive inotrope and balanced vasodilator)


What is another name for Pimobendan?



What drug is the drug of choice as an inotrope? Why?

Pimobendan, Because it's safer than digitalis (less arythmogenic)


What do inodilators do?

Increase cardiac output, cardiac contractility and vasodilation


What is Pimobendans mechanism of action?

–*in failing heart, Pimobendan acts primarily by sensitization of the cardiac contractile apparatus to calcium by enhancing interaction between calcium and troponin C complex*.
– As potential to increase intracellular calcium and increase myocardial oxygen assumption because it inhibits PDE III and probably V but this effect is minimal at therapeutic doses and dogs with CHF.
– inhibition of PDE III and V in blood vessels causes balanced vasodilation in the arteries and veins which leads to a reduction in both cardiac preload and afterload.


What are the uses for Pimobendan? (3)

–Approved to treat congestive heart failure in dogs.
– Effective as an adjunctive therapy in improving the quality and length of life in dogs with heart failure due to dilated cardiomyopathy (DCM) and chronic degenerative valvular disease (CVD)
– can be used with furosemide, Spironolactone, or ACE in heart failure patients.


What are the side effects for Pimobendan?

May cause diarrhea, vomiting, incompetence, seizures, and polyuria/polydipsia. (Less arrhythmogenic than digitalis)


What are Pimobendans contraindications?(2)

– should not be used in hypertrophic cardiomyopathy
– clinical conditions where an increase of cardiac output is not physically possible.


What is Pimobendan pharmacokinetics?(4)

– absorbed rapidly upon oral ingestion and has around 60% bioavailability
– metabolically activated in the liver
– metabolites are excreted in feces with half-life of two hours
– bounded to plasma proteins


What are the four classes/drugs of vasodilators used for CHF?

Ace inhibitors, hydralazine, nitrates, prazosin.


What are the three classes of diuretics used in CHF?

Loop diuretics, thiazide diuretics, potassium retaining diuretics.


What are the three drugs that can be used that fall under the beta blockers class?
Which one is most likely to be used?

Carvedilol, Metoprolol, or atenolol.



What is Carvedilol mechanism of action?(3)

– nonselective beta blocker and Alpha one blocker
– anti-oxidant
– inhibits endothelin (ET) release


When should you use Carvedilol?

Early in treatment of CHF due to dilated cardiomyopathy to blunt the harmful effects of sympathetic nervous system on the heart


What is the drug of choice for pheochromocytoma?



Define arrhythmia.

Abnormalities in heart rate and rhythm


What are the mechanisms of arrhythmias? (3)

– Abnormal automaticity
– abnormal conduction
– disturbance in both automaticity and impulse conduction


What are the causes of arrhythmias? (9)

– imbalances of sympathetic and parasympathetic
– changes in serum potassium, calcium, or magnesium
– hypoxemia
– acidosis
– mechanical trauma
– myocardial disease (ex. CHF)
– cardiac ischemia
– myocardial infarction
– drugs


What are the two types of arrhythmias?

Tachyarrhythmias and bradyarrhythmias


List the four classifications for antiarrhythmic drugs for tachyarrhythmias?

• Class I: Sodium channel blockers (local anesthetics ‐
membrane stabilizers)
• Class II:


In your class I (sodium channel blockers) drugs with a subclass, 1A(Prolongs action potential), 1B (shortens action potential), and 1C (no effect on action potential). Give the drugs associated 1A.(3)

» Quinidine
» Procainamide
» Disopyramide


In your class I (sodium channel blockers) drugs with a subclass, 11A(Prolongs action potential), 1B (shortens action potential), and 1C (no effect on action potential). Give the drugs associated 1B.(5)Which two are the most important?

» Lidocaine
» Phenytoin
» Tocainide
» Mexiletine
» Aprinidine

Lidocaine & Phenytoin


In your class I (sodium channel blockers) drugs with a subclass, 11A(Prolongs action potential), 1B (shortens action potential), and 1C (no effect on action potential). What is an example of class 1C drugs.



List the drugs in class 2(beta blockers). (8)

– Propranolol
– Timolol
– Pindolol
– Oxyprenolol
– Alprenolol
– Atenolol
– Esmolol
– Metoprolol


List drugs in class III (potassium channel blockers). (3)

– Bretylium
– Amiodarone
– Sotalol (nonselective


List the drugs in class IV (calcium channel blockers). (2)

– Verapamil
– Diltiazem


What is the therapeutic use of quinidine? (2)

– ventricular arrhythmias
–* drug of choice atrial fibrillation horses, cattle and large breeds of dogs.D


What is the therapeutic uses for Procainamide?

It is effective for ventricular arrhythmias.


What is the therapeutic uses for lidocaine? (2)

–Is the drug of choice for ventricular arrhythmias due to general anesthetics, surgery, ischemia, and the trauma.
– Digitalis induced arrhythmias


What is the therapeutic use for phenytoin?T

Digitalis induced arrhythmias *Dogs Only*


What is the therapeutic use for propranolol? (4)

• *Drug of choice for supraventricular and ventricular tachycardia in cats*
• Digitalis‐induced tachyarrhythmias
• Arrhythmias due to inhalation anesthesia
• *drug of choice for hyperthyroidism in cats*


What is the therapeutic use for Bretylium, Verapamil and diltiazem?

Bretylium:Refractory and recurrent tachyarrhythmias
Verapamil and diltiazem: supraventricular tachyarrhythmias, myocardial hypertrophy


Look at slides 56 –58, 60 – 69, 83-84, 88, 100-102

They are just list of drugs


What are the drugs of choice for both supra ventricular and ventricular tachyrrhythmias? O

Beta blockers


What are the mechanisms of action ACE inhibitors? (7) i

–Inhibition of angiotensin-converting enzyme (kinase)
– inhibition of angiotensin II synthesis
– inhibition of aldosterone
– reflex increase in renin
– increased bradykinin level (vasodilator and stimulates PG's biosynthesis which is also a vasodilator)
– our local tissue specific renin angiotensin system's (RASs) in the heart, kidney, brain, adrenal and other tissues
– the local RASs in these tissues may be more important than the systemic RAS


What are some ACE inhibitors therapeutic uses? (3)

– congestive heart failure
– drug of choice for hypertension in dogs
– chronic renal insufficiency and cats (benazepril
approved in Canada)


How can you tell if a drug is an ACE inhibitor?D

It ends in pril.


What is the ACE inhibitors pharmacokinetics? (3)

– Enalapril is available orally and parenterally but others are only oral
– Food reduces intestinal absorption of captopril
– Enalapril has a slower onset and longer duration of action than captopril in the dog (administered 1‐2 times daily)


Which ACE inhibitors are long-acting?
A. Benazepril
B. Captopril
C. lisinopril
D. Two of the above
E. all of the above

E (A and C)
*Administer once daily


Which ACE inhibitors are activated in the liver?
A. Benazepril
B. Captopril
C. Enalapril
D. Two of the above
E. all of the above

E (A and C)


Why is Benazepril least likely to require dosage modification in renal failure patience?

It is significantly excreted bile (50%)P


What are ACE inhibitors adverse effects? (2)

– Hypotension
– ACE inhibitors may lower intraglomerular pressure decreasing GFR in animals with systemic hypertension and azotemia

*coughing due to ACE inhibitors does not seem to be a problem in dogs and cats.


What is captopril Adverse Effects? (3)

– Captopril may cause idiosyncratic glomerular disease in some dogs
– Captopril has more GI side effects than enalapril
– Captopril (‐SH group) may cause neutropenia, proteinuria and skin rash in some humans


Name to direct acting vasodilators. Which does arteries only?

Hydralazine (arteriolar vasodilator) and nitrates.
*Both can be used in emergency hypertension case (hypertensive crisis)



What is hydralazine mechanism of action?H

– Increasing local concentrations of PGI2
– May be by inhibiting calcium influx into smooth muscles of arteries


What is the mechanism of action for nitrates?

– Formation of the reactive radical nitric oxide (NO) which activates guanylyl cyclase
– increased cyclic GMP
– stimulation of GMP depended protein kinase

*balanced alpha one antagonist. Treatment for pulmonary hypertension and angina (chest pain). A


What is the drug of choice for pheochromocytoma?I



List the three classifications for calcium channel blockers (CCBS). Give an example of each classification.

– Diphenyl alkylamines
• Verapamil
– Benzodiazepines
• Diltiazem
– Dihydropyridines
• Amlodipine
• Nifedipine


What is the CCBS mechanism of action?

Inhibit the influx of extracellular calcium across myocardial and smooth muscle cell membranes. Decrease in intracellular calcium inhibits myocardial contraction results in violation of the coronary and systemic arteries


What is the CCBS pharmacological effects on the heart? (5)

*• Negative inotropic effect*
*• Negative chronotropic effect*
• Increase oxygen delivery to the myocardial tissue
• Decrease after load
• Coronary vasodilation


What are the CCBS's therapeutic uses? (4)

– Antiarrhythmic (Class IV)
• Verapamil and diltiazem are used in the treatment of supraventricular tachyarrhythmias
– Antihypertensive
• Amlopdipine is recommended as the first‐line antihypertensive in cats unless the cause is hyperthyroidism, in this case a


What is the drug of choice in cats for myocardial hypertrophy?



What should first be used in hypertensive cats? If it has hyperthyroidism what should you use?

Use a beta blocker


What are CCBS adverse effects? (4)

– Bradycardia and AV block
– Hypotension
– GI side effects
– Elevated liver enzymes (temporary)