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Veterinary Pharmacology > Cardiovascular Pharmacology, Pt. 2 > Flashcards

Cardiovascular Pharmacology, Pt. 2 Flashcards

1
Q

What mineralocorticoid receptor blocker is used to treat cardiac disease? What is its mechanism of action? What are 3 results?

A

Spironolactone - antagonizes intracytoplasmis aldosterone receptors in the late DCT and CD, which causes a decrease n ENAC and Na/K ATPase metabolism

  1. increased water excretion
  2. increased urinary Na+
  3. decreased K+ excretion (potassium-sparing)
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2
Q

What are the main 2 cardiovascular clinical use of Spironolactone? How is it used in cats?

A
  1. dogs with myxomatous mitral valve disease
  2. adjunctive therapy in dogs with ACVIM B2-D2

extra-label use to decrease aldosterone concentrations in Maine Coons with asymptomatic HCM

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3
Q

What are 2 common vasodilators used to treat cardiovascular disease? What are their mechanisms of action?

A
  1. Prazosin: α-antagonist that blocks vascular smooth muscle contraction
  2. Hydralazine hydrochloride: relaxes arteriolar smooth muscle with litter effect on the venous system
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4
Q

What are the 2 main cardiovascular indications for Prazosin usage?

A
  1. renal hypertension
  2. vesicourethral reflex dyssynergia
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5
Q

What are the 2 primary usages as Hydralazine hydrochloride (Apresoline)? What adverse effects have been associated with its usage?

A
  1. afterload reducer for adjunctive treatment of CHF
  2. antihypertensive agent in dogs and cats

tachycardia and hypotension

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6
Q

What calcium channel blocker is used to treat cardiovascular disease? What is its mechanism of action? What are 4 results?

A

Amlodipine - suppresses calcium ion influx through PM channels in myocardial cells, vascular smooth muscle, and other excitable cells

  1. reduction in myocardial contractility
  2. vasodilation in peripheral arterial beds
  3. reduced myocardial oxygen demand
  4. slowed AV impulse conduction
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7
Q

What is Amlodipine the preferred treatment for What adverse effects are associated?

A

systemic hypertension in cats

negative inotropic effects and vasodilator actions benefit hemodynamics to decrease cardiac workload, which can exacerbate hypotensive crisis (can be managed by altering dosage or dropping other drugs)

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8
Q

What nitrovasodilator is commonly used to treat cardiovascular disease? What is their mechanism of action?

A

nitroglycerine (nitrogen esters)

act as exogenous sources of nitric oxide (endothelium-derived relaxing factor, endogenous vasodilator) and activate guanylate cyclase, leading to the formation of cyclic guanosine monophosphate (cGMP) from GTP

  • inhibits the contraction of vascular smooth muscle by decreasing the availability of calcium and interferes with myosin-actin interaction
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9
Q

What are 2 additional mechanisms of action of nitroglycerin and nitrovasodilators? What is the main indication?

A
  1. stimulate the synthesis of vasodilators PGI2 and PGE
  2. decrease myocardial O2 requirements to decrease the workload of the heart

short-term management of acute heart failure

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10
Q

What is the recommended route of administration of nitrovasodilators?

A

sublingual, topical, IV —> short half-life, significant first pass effects

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11
Q

Where is it recommended to apply topical nitroglycerin? What oral nitrovasodilators are available?

A

areas that lack hair, like the groin, axillary area, or ear pinna, or shaved portion of the body —> owners should wear exam gloves and thoroughly wash hands

  • Isosorbide dinitrate
  • Isosorbide mononitrate: better absorption
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12
Q

What phosphodiesterase type 5 inhibitor is used to treat cardiovascular disease? What is its mechanism of action? What is its main indication?

A

Sildenafil - prevents the degradation of cGMP, allowing for smooth muscle relaxation in pulmonary vasculature and systemic vessels (enhances nitrovasodilators)

pulmonary hypertension that is often a sequalae of chronic obstructive pulmonary disease, MMVD, and heartworm disease

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13
Q

What other drugs is Sildenafil commonly combined with? What are the 2 results of this combination?

A
  • Furosemide
  • Enalapril
  • Pimobendan
  • Digoxin
  • Spironolactone
  • Thiazide diuretics
  1. decreases systolic pulmonary arterial pressure
  2. increases exercise capacity and quality of life
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14
Q

What β-adrenergic receptor antagonist is used to treat cardiovascular disease? What is its mechanism of action? What are some adverse effects?

A

Carvedilol (β1 = β2 > α1 > α2) - decreases SNS activity causing reduced myocardial workload and a decreased heart rate and peripheral vascular resistance

  • tachycardia and arrhythmias
  • vasoconstriction with increased afterload
  • RAAS activation
  • myocardial remodeling
  • fibrosis
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15
Q

What is the main indication for Carvedilol usage? How does the dosage change its effect?

A

experimental mitral valve regurgitation

  • LOWER DOSE = decreased heart rate
  • HIGHER DOSE = decreased heart rate, renal function, and arterial blood pressure
  • start with a low dose and increase until target dose is reached without adverse effects
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16
Q

What additional therapy is recommended for congestive heart failure? What are the main 2 supplement combinations?

A

potent loop diuretics - Furosemide, Torsemide, Butemide

  1. TRIPLE THERAPY = ACEIs and pimobendane
  2. QUADRUPLE THERAPY = ACEIs, pimobendane, spironolactone
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17
Q

Why should patients on diuretics always be monitored? What further exacerbates this effect?

A

pronounced diuresis can reduce blood volume and lower preload (ventricular filling pressure), causing tension, increased myocardial oxygen demand, and predisposition for edema + decreased venous return leads to decreased cardiac output, renal perfusion, and drug clearance, and azotemia

inappetence and vomiting —> electrolyte loss

18
Q

What 4 parameters are monitored in patients on diuretics for congestive heart failure?

A
  1. serum electrolytes
  2. renal values - BUN, creatinine
  3. body weight
  4. state of hydration - skin turgor, PCV, TP, albumin, sodium
19
Q

What is characteristic of heart failure, MMVD, and DCM?

A

SNS and RAAS activation, elevated preload and afterload, high heart rate

contractility is maintained until the terminal stages

diminished contractility (required inotropic support with dobutamine CRI, digoxin, or pimobendan)

20
Q

What is an arrhythmia? What can they lead to?

A

abnormality in the rate, regularity, or site of origin of electric impulses

very slow, rapid, or irregular heart rates of clinical importance is present with cardiac disease

21
Q

What are 4 possible causes of arrhythmias?

A
  1. imbalance of the PSNS and SNS
  2. changes in serum electrolyte concentrations (K, Ca)
  3. excessive stretch of cardiac tissue
  4. mechanical trauma
22
Q

What are the 4 classes of antiarrhythmic drugs?

A

I - local anesthetics

II - β-adrenergic blockers

III - potassium channel blockers

IV - calcium channel blockers

23
Q

What are the 2 goals of treating bradyarrhythmias?

A
  1. decrease vagal tone (vagolytics)
  2. increase sympathetic tones
24
Q

What are the 3 types of tachyarrhythmias? What drugs are used to treat each?

A
  1. sinus tachycardia - Pimobendan, ACEIs
  2. supraventricular tachyarrhythmias - Digoxin, Diltiazem (IV), Atenolol, Esmolol, Sotalol (II)
  3. ventricular tachyarrhythmias - Lidocaine (I), Mexiletine (I), Sotalol (II)
25
Q

What 2 vagolytics are used to treat bradyarrhythmia?

A
  1. Atropine
  2. Propanntheline bromide - antimuscarinic that is variably absorbed in the GIT and can lead to tachycardia, increased salivation, or vomiting
26
Q

What β-adrenergic agonist is used to treat bradycardia?

A

Isoproterenol (ISO) - β1 > β2&raquo_space;» α

  • increases heart rate by stimulated adrenergic receptors (β1, β2) in the sinus and atrioventricular node
27
Q

How is Isoproterenol administered? What are 2 common adverse effects?

A

IV for short-term treatment (CRI)

  1. hypotension
  2. arrhythmias
  • blood pressure and electrocardiography monitoring
28
Q

What are 5 causes of sinus tachycardia?

A
  1. low blood pressure
  2. pain
  3. sepsis
  4. fever
  5. low cardiac output
29
Q

What cardiovascular disease commonly causes sinus tachycardia? What drugs are indicated for treatment?

A

CHF —> low cardiac output

Pimobendan and ACEIs

30
Q

What is the most common cause of supraventricular tachyarrhythmias? What kind of treatment is indicated?

A

primary cardiac disease and secondary atrial enlargement

not likely to resolve with antiarrhythmic drugs - slow down the rapid conduction through AV node with digitalis, calcium channel blockers, or β-adrenergic blockers

31
Q

What digitalis is used to treat supraventricular tachyarrhythmias? What is its mechanism of action? How should treatment be done with CHF or myocardial dysfunction?

A

Digoxin - slows conduction of the AV node and slows ventricular response rate (decreased HR is not significant, so it needs class II or IV drugs also)

give digoxin, then atenolol or diltiazem once stablized

32
Q

What 2 calcium channel blockers are used to treat supraventricular tachyarrhythmias? What effect do they have? What are the adverse effects seen in dogs and cats?

A

Diltiazem and Verapamil

slows the ventricular response rate

RARE:
- DOGS = bradycardia, AV block
- CATS = GI signs (vomiting, diarrhea)

33
Q

What are the 3 most common β-adrenergic blockers used to treat supraventricular tachyarrhythmias?

A
  1. Atenolol
  2. Esmolol
  3. Sotalol
34
Q

How is Atenolol used to treat supraventricular tachyarrhythmias? What do high doses lead to? What is it commonly used with?

A

specific β1 blocker that acts as a negative inotrope

bradycardia, exacerbates heart failure or myocardial dysfunction

Digoxin - slows the heart rate of patients with atrial fibrillation or rapid SVTA —> requires 24 hr Holter monitoring

35
Q

How is Esmolol used to treat supraventricular tachyarrhythmias? What adverse effect is associated?

A

ultrashort-acting blocker used for IV administration for acute termination of SVTA

sinus bradycardia, decreased myocardial function, abrupt sinus arrest

36
Q

How is Sotalol used to treat supraventricular tachyarrhythmias? How does it compare to other β-antagonists? What is it commonly combined with?

A

non-selective β-blocker and potassium channel blocker (II and III)

prolongs cardiac AP and QT intervals by delaying the slow outward K+ current for SVTA and VTA treatment

VERY SAFE AND EFFECTIVE - Mexiletine for refractory arrhythmias

37
Q

What is the goal of treating ventricular tachyarrhythmias? What drugs are used to do this?

A

decrease the number of abnormal ventricular complexes

local anesthetics (IB) - Lidocaine, Mexiletine

38
Q

How is Lidocaine able to treat ventricular tachyarrhythmias? Why is it only administered IV? What side effects are most common?

A

inhibits the inward sodium current and reduces the rate of AP rise

very high first-pass metabolism in the liver (not effective if administered orally)

neurological - depression, seizures, vomiting

39
Q

What is the most useful local anesthetic used to treat ventricular tachyarrhythmias? What are the most common adverse effects?

A

Mexiletine

  • neurological: depression, seizures, vomiting
  • GI: mild loss of appetite or vomiting*
40
Q

How does Mexiletine compare to Lidocaine? What is it commonly combined with?

A

good oral absorption —> can be give as oral capsules

Sotalol

41
Q

Calcium channel blockers classifiction

A
  • Non-dihydropyridines: verapamil and diltiazem
  • Dihydropyridines: amlodipine and nicardapine

Veterinary Pharmacology (35 decks)

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