Vasodilators Pharmacology

Front 1

What are 2 mixed vasodilators?

Back 1

1) Nitroprussiate
2) ACE inhibitors

Front 2

What are 3 kinds of vasodilators?

Back 2

1) Hydralazine
2) Calcium-channel blockers
3) Alpha1-adrenoreceptor blockers

Front 3

What is the equation for pressure?

Back 3

Pressure=flow x resistance
Flow=cardiac output
Resistance=degree of vasoconstriction

Front 4

What are the effects of arterial dilators? Venous dilators?

Back 4

Arterial dilators decrease arterial pressure, venodilators decrease venous pressure

Front 5

What are 3 ways to reduce hypertension?

Back 5

1) Decreasing cardiac function (beta blockers)
2) Decrease flow by decreasing volume w/ diuretics
3) Vasodilation

Front 6

What are the 2 main uses of arterial dilators?

Back 6

1) Decrease blood pressure
-systemic hypertension
2) Increase cardiac output
-Heart failure

Front 7

What calcium channel blocker is most commonly used?

Back 7

A dihydropyridine-Amlodipine

Front 8

What is the mechanism of action of amlodipine?

Back 8

Blocks primarily calcium channels in systemic arteriolar smooth muscle
-Arterial vasodilation
-Almost no effect on the heart

Front 9

True or false. Amlodipine has almost no effect on the heart.

Back 9

True

Front 10

What is the drug of choice for hypertension in a cat?

Back 10

Amlodipine

Front 11

What are 2 clinical uses of amlodipine?

Back 11

1) Primarily to treat hypertension
1st choice in cats, very effective in dogs
2) Decrease mitral regurgitation in dogs
-Rarely used

Front 12

What is the oral bioavailability of amlodipine in dogs?

Back 12

90%

Front 13

True or false. Amlodipine is not very highly protein bound, less than 50%.

Back 13

False, 95% protein bound

Front 14

What is the adverse effect of amlodipine?

Back 14

Hypotension

Front 15

What is the mechanism of action of hydralazine?

Back 15

Direct vasodilator, likely by increasing prostacyclin concentration
-Very potent vasodilator

Front 16

What are 2 clinical uses of hydralazine?

Back 16

1) Primarily to treat hypertension
-Hypertensive crisis (IV)
-Refractory hypertension
2) Decrease mitral regurgitation in dogs with mitral valve disease
-Refractory failure

Front 17

What is the oral absorption like wit hydralazine?

Back 17

Good, but undergoes first pass hepatic metabolism

Front 18

What is your second and third choice for hypertension in a cat?

Back 18

2nd-ACE inhibitors
3rd-Hydralazine

Front 19

When do the effects of hydralazine begin? How long is the animal stable? How long does it last?

Back 19

Begins in 30-60 minutes
Stable for 8-10 hours
Lasts 12 h

Front 20

What is the dosage interval of hydralazine?

Back 20

Must be titrated

Front 21

What are 3 adverse effects of hydralazine?

Back 21

1) Hypotension
2) Anorexia and vomiting
3) Reflex tachycardia

Front 22

What drug is an alpha1-adrenoreceptor blocker?

Back 22

Prazosin

Front 23

True or false. Prazosin is used commonly in dogs, but not in cats.

Back 23

False, rarely used in dogs, never used in cats

Front 24

True or false. Prazosin is a vasodilator.

Back 24

False, arteriolar and venodilator

Front 25

What are 2 clinical uses of prazosin?

Back 25

1) Arterial hypertension
-Refractory
2) Urethral relaxation
-Other drugs are safer

Front 26

True or false. ACE inhibitors are commonly used.

Back 26

True

Front 27

ACE inhibitors prolong survival in ______ failure and ______ failure.

Back 27

Heart failure
Renal failure (increases renal perfusion)

Front 28

True or false. ACE inhibitors are a potent vasodilator.

Back 28

False, mixed dilator and not very potent, with weak hemodynamic effects

Front 29

What are 4 examples of ACE inhibitors?

Back 29

1) *Enalapril
2) Benazepril
3) Ramipril
4) Lisinopril

Front 30

What is the mechanism of action of ACE inhibitors?

Back 30

Systemic and local ACE inhibition

Front 31

What are 3 clinical uses of ACE inhibitors?

Back 31

1) Systemic hypertension
2) Heart failure
-Neuroendocrine modulation
3) Renal failure
-Increases survival
-Proteinuria

Front 32

When are ACE inhibitors the first drug of choice for systemic hypertension?

Back 32

For nephroprotection:
-Proteinuria
-Renal failure

Front 33

What is the vasodilator of choice for heart failure?

Back 33

ACE inhibitors

Front 34

What is the bioavailability of enalapril? What is it metabolized to?

Back 34

60%, metabolized to enalaprilat

Front 35

How are ACE inhibitors eliminated?

Back 35

Renal excretion

Front 36

What is the bioavailability of Benazepril? What's it metabolized to?

Back 36

35%, metabolized to benazeprilat

Front 37

How is benazepril eliminated?

Back 37

Renal and biliary excretion

Front 38

What are 3 adverse effects of ACE inhibitors?

Back 38

1) Hypotension (rare)
2) Anorexia & vomiting
3) Renal failure
-Patients that are volume depleted
*stabilize patient first!