Directly acting vasodilators

Question 1

what are the different types of vasodilators

Answer 1

calcium channel blockers (dihydropyridine and non-dihydropyridine), hydralazine, potassium channel agonists (minoxidil), nitrates

Question 2

what is the GENERAL mechanism of all vasodilators

Answer 2

they act directly on vascular smooth muscle cells and reduce the magnitude of smooth muscle contraction—> reducing the myogenic tone of the cells, resulting in vasodilation

Question 3

the major difference between DHP and nDHP is _____

Answer 3

nDHP’s also decrease heart rate

Question 4

what are the dihydropyridines

Answer 4

amlodipine, felodipine, isradipine, nicardipine, cifedipine, nimodipine, clevidipine

Question 5

what are the non-dihydropyridines

Answer 5

diltiazem, verapamil

Question 6

diltiazem is a _____

Answer 6

benzothiazepine

Question 7

verapamil is a ______

Answer 7

phenylalkylamine

Question 8

calcium channel blockers bind to ______ calcium channels

Answer 8

voltage-sensitive, L-type

Question 9

which subunit of the calcium channel do CCBs bind to

Answer 9

the alpha 1 subunit (part that forms the pore thru which calcium passes)

Question 10

CCBs binding to the L-type calcium channel causes it to _____

Answer 10

stay in the closed inactivated conformation

Question 11

what is the result of CCBs inactivating channels

Answer 11

less calcium can enter smooth muscle cells, which decreases contraction

Question 12

contractions depend on ____

Answer 12

availability of calcium

Question 13

CCBs relax the vascular smooth muscle of _______, which reduces ___

Answer 13

arteries and arterioles, TPR

Question 14

the vascular smooth muscle of ____ is NOT significantly affected by CCBs

Answer 14

veins

Question 15

CCBs are especially useful for patients with _____

Answer 15

LOW renin

Question 16

clinical uses of CCB

Answer 16

use alone or in combo, effective in reducing BP, also useful in the treatment of coronary artery disease

Question 17

why are CCBs useful in coronary artery disease

Answer 17

since they are able to relax coronary arteries and increase blood flow to the heart muscle. since they lower BP, they reduce the work that the heart must do to provide the energy to move blood through the blood vessels

Question 18

when are CCBs a great alternative to BBs

Answer 18

for patients with asthma

Question 19

which CCB should you NOT combine w/ a BB and why?

Answer 19

nDHP–> because they both lower heart rate

Question 20

diltiazem and verapamil are also used to treat _____

Answer 20

arrhythmias

Question 21

dihydropyridines do not have a major effect on ________, so they are not used as antiarrhythmics

Answer 21

AV node conduction

Question 22

what is a side effect with CCBs

Answer 22

peripheral edema (ankles in particular)

Question 23

how would CCBs cause peripheral edema

Answer 23

they relax the small arterioles leading into capillaries but not the veins leading out of the capillary bed–> which elevates the hydrostatic pressure within the capillary and favors leakage of fluid into interstitial space

Question 24

which patients should not take CCBs

Answer 24

in heart failure patients, the decrease in contractility could depress cardiac function. in patients with cardiac disease that is associated with AV node conduction, they are a bad choice as they can further reduce AV node conduction

Question 25

what is the mechanism of hydralazine

Answer 25

it enters vascular smooth muscle cells--> keeps Ca channels closed--> blocks release of Ca from sarcoplasmic reticulum--> reduces cytoplasmic Ca concentration--> reduces contraction

Question 26

hydralazine has an affect on ____ smooth muscle which decreases ____

Answer 26

arterial; TPR

Question 27

hydralazine has no effect on ____ smooth muscle

Answer 27

venous

Question 28

what is an adverse effect of hydralazine

Answer 28

systemic lupus erythematosus-like syndrome (an antibody response causing rash and muscle pain)

Question 29

what are the clinical uses of hydralazine in HTN

Answer 29

reserved for pts whose HTN is refractory to treatment with other agents

Question 30

hydralazine can be combined with ______ to prevent sympathetic reflex activation

Answer 30

beta blockers

Question 31

hydralazine can be combined with a _____ to prevent sodium retention

Answer 31

diuretic

Question 32

hydralazine can be combined with ______ for heart failure

Answer 32

isosorbide dinitrate

Question 33

what is the mechanism of minoxidil

Answer 33

potassium channel agonist--> K channel opens--> more negative membrane potential--> more voltage gated L-type calcium channels will be closed---> less Ca will enter the cells---> smooth muscle relaxed

Question 34

minoxidil is a potent _____ vasodilator that decreases ____

Answer 34

arterial, TPR

Question 35

minoxidil has no significant effect on ____ smooth muscle

Answer 35

venous

Question 36

how does sympathetic reflex activation work against the vasodilators

Answer 36

baroreceptors detect the decrease in blood pressure and compensate

Question 37

use of minoxidil in HTN

Answer 37

reserved for complicated patients

Question 38

adverse effect of minoxidil

Answer 38

hypertrichosis (hair growth)--> rogaine

Question 39

what are the nitrates

Answer 39

nitroglycerin, isosorbide dinitrate, isosorbide mononitrate, sodium nitroprusside

Question 40

use of sodium nitroprusside

Answer 40

hypertensive emergencies

Question 41

use of nitroglycerin

Answer 41

coronary artery disease (chronic stable angina and acute MI)

Question 42

use of isosorbide mononitrate & dinitrate

Answer 42

chronic stable angina

Question 43

the metabolism of nitrates and sodium nitroprusside leads to intracellular production of _____ in vascular smooth muscle

Answer 43

nitric oxide

Question 44

nitric oxide stimulates _____

Answer 44

guanylate cyclase

Question 45

the increased production of ______ by guanylate cyclase causes cytoplasmic Ca to decrease

Answer 45

cyclic GMP

Question 46

it has been hypothesized that impaired formation of _____ may be a cause of hypertension

Answer 46

nitric oxide

Question 47

what are symptoms of sodium nitroprusside toxicity

Answer 47

metabolic acidosis, decreased oxygen saturation, bradycardia, confusion, convulsions

Question 48

when does toxicity occur with sodium nitroprusside

Answer 48

high doses, long term administration, poor liver/kidney function

Question 49

what is the mechanism of sodium nitroprusside toxicity

Answer 49

it is made up of ferric cyanide and nitric oxide--> cyanide is released into the bloodstream, then further metabolized by the liver to thiocyanate which is then slowly cleared by the kidneys