Chapter 40 Vasodilators

Question 1

What effects do vasodilator drugs have

Answer 1

they act directly on the smooth muscles in arterioles and veins to produce vessel relaxation

Question 2

What do hydralazine and minoxidil cause dilation of?

Answer 2

selective dilation of arterioles

Question 3

What does Nitroprusside cause dilation of?

Answer 3

arterioles and veins

Question 4

If a drug dilates arterioles what are the effects?

Answer 4

decrease in cardiac afterload (the force the heart works against to pump blood).

Question 5

If drugs dilate capacitance vessels (veins) what are the effects

Answer 5

reduce the force with which blood is returned to the heart, which reduce ventricular filling. This reduction in filling decreases cardiac preload (the degree of stretch of the ventricular muscle before contraction), which decreases the force of ventricular contraction.

Question 6

Vasodilators therapeutic uses

Answer 6

essential htn, htn crisis, angina pectoris, heart failure, and MI

Question 7

AE of vasodilation

Answer 7

postural hypotension-

caused by venous relaxation, gravity causes blood to pool in the veins, thereby decreasing venous return to the heart, which causes decreased cardiac output, and decrease in blood pressure

minimal in recumbent subjects because the effect of gravity on venous return is small when we are lying down.

Question 8

Hydralazine Cardiovascular Effects

Answer 8

selective dilation of arterioles (little no effects on veins)

dilation results from direct action on VSM (vascular smooth muscle)

peripheral resistance and arterial blood pressure fall, while HR and myocardial contractility increase d/t reflex mechanism -> means decreased cardiac output

postural hypotension is minimal bc it works selectively on arterioles

Question 9

Hydralazine Kinetics

Answer 9

PO: effects begin within 45 minutes and persist for six hours or longer

Parenteral admin: effects begin faster (within 10 minutes) and last 2 to 4 hours.

Question 10

Hydralazine Metabolism

Answer 10

inactivated by a metabolic process known as acetylation - either genetically slower or faster. -

if slow - higher drug in serum
if fast - lower

genetically determined

Question 11

What would occur in a person who metabolized hydral slowly due to acetylate?

Answer 11

excessive vasodilation with undersired effects

reduce drug in slow acetylators

Question 12

Therapeutic uses of hydralazine

Answer 12

lower blood pressure in patients with essential hypertension

regimen almost always included a B blocker, used largely in the past but now replaced by newer antihypertensive agents.

Heart failure- reduce afterload in pt with hf, tolerence develops (usually used with isosorbide dinitrate)

Question 13

AE of hydralazine

Answer 13

trigger reflex stimulation of the heart, thereby causing cardiac work and myocardial oxygen demand to increase
bc hydralazine induced REFLEX TACHYCARDIA is frequently severe, usually combined with a b blocker

Systemic Lupus erythematosus-like syndrome (symptoms include muscle pain, joint pain, fever, nephritis, pericarditis - SMA SYPTOMS -discontinue drug in this case

most likely in slow metabolizers, d/c hydral if it occurs

usually reversible - may take a long time for SMA symptoms to resolve

Question 14

Hydral drug interactions

Answer 14

combined with a B blocker to protect agaisnt reflex tachycardia and a combined with a diuretic to prevent na and water retention and expansion of blood volume

if used with other hypotensive medications care is needed to prevent excessive hypotension

in HF combined with isosorbide dinitrate (dilates veins)

Question 15

What patient would you use minoxidil for?

Answer 15

severe hypertension unresponsive to other drugs

d/t intense vasodilation with more severe adverse reactions

Question 16

Minoxidil cardiovascular effects

Answer 16

selective dilation of arterioles little or no venous dilation occurs

-arteriolar dilation decreases perpheral resistance and arterial pressure
-so
increase HR and myocardial contractility

Which increase cardiac oxygen demand and can make angina worse

Question 17

What must minoxidle be metabolized to in order to make the drug effective?

Answer 17

minxidil sulfate which causes k channels to open which hyperpolarizes VSM cells, which reduces their ability to contract

Question 18

Minoxidil Kinetics

Answer 18

maximum vaso within 2-3 hrs then gradually declines.effects may continue 2-3 days.

metabolites and parent drug are eliminated in the urine

half life 4.2 hours

Question 19

Minoxidil therapeutic uses

Answer 19

severe hypertension reserved only for pts who have not responded to safer drugs

Question 20

What drug do you combine with minoxidil to minimize adverse effects?

Answer 20

b blockers and intensive diuretic therapy (loop diuretic alone or in combo with a thiazide diuretic)

if that doesn’t work - dialysis, then or d/c drug

Question 21

AE of minoxidil

Answer 21

reflex tachycardia- combine with b blocker

na and water retention- volume expansion may be so severe as to cause cardiac decompensation. Must give with diuretics (loop and/ or thiazide) if not effective pt must be put on dialysis or minoxidil withdrawn

hypertrichosis- excessive hair growth (Rogaine)

Question 22

What is the black box warning for minoxidil?

Answer 22

can cause pericardial effusion, occasionally progressing to tamponade, and may exacerbate angina pectoris

Question 23

What should be monitored on a daily bases for patient taking vasodilators?

Answer 23

blood pressure and heart rate

for minoxidil- also include daily weights

Question 24

Vasodilators and pregnant

Answer 24

Avoid if possible

Question 25

what patient education should be given to patients taking vasodilators?

Answer 25

cautioned to stand up slowly so as to avoid postural hypotension

Question 26

How would you evaluate if vasodilators had been effective?

Answer 26

monitor for reduced blood pressure, monitor for s/s of heart failure including dyspnea.

Question 27

Vasodilators across the life span

Answer 27

infants; young as one month

children: smaller doses can be safe
pregnant: risk vs. benefit

breastfeeding women: data are lacking regarding transmission of drug from mother to infant bm

older adults: monitor for falls d/t polypharmacy and orthostatic hypotension

Question 28

What do you give for severe hypertensive crisis

Answer 28

Nitropress IV

Question 29

Which meds produce postural hypotension

minoxidil
diltiazem
prazosin
captopril
losartan

Answer 29

prazosin
captopril
losartan