Pharmacology 11: Antihypertensive Drugs

Front 1

What is the equation for BP?

Back 1

BP = CO x PVR; cardiac output x resistance

Front 2

How do carotid baroreceptors detect BP?

Back 2

detect changes in the stretch of the vessel walls

Front 3

When going from lying down to standing up, what happens to sympathetics?

Back 3

increase to keep BP high near carotid sinus

Front 4

Endothelin has what effect on vessels?

Back 4

constricts vessels

Front 5

What are sympathetoplegic agents?

Back 5

lower BP by reducing resistance and cardiac output; sympathetoplegic means paralyzing the sympathetics (the sympathetics increase BP so we want to lower sympathetics to decrease BP)

Front 6

How do diuretics help hypertension?

Back 6

keep sodium of the blood so water doesn't stay in; remove water from the system

Front 7

Which class of diuretics is the strongest?

Back 7

loop diuretics (furosemide)

Front 8

How does the drug clonidine work?

Back 8

stimulates a-adrenoreceptors in medulla of brain to reduce sympathetic tone

Front 9

Where does methyldopa work to decrease BP?

Back 9

central nervous system, reduces sympathetic tone

Front 10

How do ganglion blocking agents reduce BP?

Back 10

inhibit nicotinic choline receptors on post ganglionic neurons = lower sympathetic tone (but also parasympathetic tone is low)

Front 11

How do adrenergic neuron blocking agents work to decrease BP?

Back 11

prevent norepinephrine release from post ganglionic sympathetic neurons

Front 12

How does guanethidine work?

Back 12

prevent norepinephrine release from post ganglionic sympathetic neurons. enters postsynaptic neuron and concentrates and replaces norepinephrine in the nerve ending vesicles. thus uptake into the neuron is essential for this drug

Front 13

Why does guanethidine not work if a patient is smoking rocks (cocaine)?

Back 13

cocaine inhibits uptake of neurotransmitters in the synaptic membrane; guanethidine must be taken into the neuron to displace norepinephrine in the synaptic vesicles

Front 14

Why is diarrhea common in patients on guanethidine?

Back 14

with sympathetics "shut-off", the parasympathetics take over the body

Front 15

What type of drug is reserpine?

Back 15

adrenergic neuron blocking agent; interferes with VMAT (transports vesicles across membrane of neurons = no sympathetic neurotransmitter vesicles)

Front 16

How do Beta blockers decrease BP?

Back 16

they block sympathetic receptors (for epi/norepi) = decreasing cardiac output = decreased BP

Front 17

Why are metoprolol and atenolol better B-blockers than propanolol?

Back 17

they are cardio-selective and have less side effects

Front 18

How does prazosin or terazosin work to decrease BP?

Back 18

alpha1 blocker in vessels. alpha receptors bind sympathetics and cause constriction. if they are blocked, we have less constriction

Front 19

What is the difference between phentolamine and prazosin?

Back 19

phentolamine is a non-selective a-blocker; prazosin works in arterioles/venules

Front 20

How does hydralazine work to decrease BP?

Back 20

stimulates release of NO from endothelium to vasodilate

Front 21

How does minoxidil work to decrease BP?

Back 21

vasodilator; opens potassium channels to further lower resting potential of smooth muscle neurons = less smooth muscle contraction

Front 22

How does nitroprusside work to decrease BP?

Back 22

vasodilator; increase cGMP activity = more relaxed smooth muscle

Front 23

How does diazoxide work to decrease BP?

Back 23

vasodilator; opens potasssium channels = less likely smooth muscle contraction

Front 24

How does fenoldopam work to decrease BP?

Back 24

D1 dopamine receptor agonist; D1 receptors = more cAMP = smooth muscle relaxation = dilates arteries

Front 25

How do calcium channel blockers (diltiazem, verapamil, nifedipine) work to decrease BP?

Back 25

prevent calcium influx in smooth muscle neurons = less likely to hit threshold = less smooth muscle contraction = dilation. also decreases heart rate/cardiac output

Front 26

What calcium blocker has more effect on the vessels for vasodilation? Diltiazem of Nifedipine?

Back 26

Nifedipine works more on the smooth muscle relaxation

Front 27

How does Captopril work to decrease BP?

Back 27

ACE inhibitor; prevent angiotensin 2 production (angiotensin 2 = more aldosterone = more volume. also vasoconstrictor)

Front 28

What is the advantage to decreasing BP by angiotensin 2 inhibition vs. directly decreasing cardiac output or resistance?

Back 28

direct changes usually result in reflexive sympathetic responses when BP falls

Front 29

How do Losartan and Valsartan work to decrease BP?

Back 29

block angiotensin receptors so angiotensin 2 cannot vasoconstrict vessels

Front 30

Which class of antihypertensive drugs works most on the activation of the bradykinin system to vasodilate?

Back 30

ACE inhibitors

Front 31

How do ACE inhibitors promote vasodilation through the bradykinin system?

Back 31

prevent formation of inactive metabolites and force production of prostaglandins (vasodilators)

Front 32

Normal BP

Back 32

120/80

Front 33

Prehypertensive BP

Back 33

120-135/80-89

Front 34

Hypertensive BP

Back 34

140+/90+

Front 35

Stage 2 hypertensive BP

Back 35

160+/100+

Front 36

Why is it common to prescribe multiple drugs to treat hypertension?

Back 36

one drug may elicit a compensatory mechanism to keep BP high. (e.g. if a vasodilator is given, a patient may have more renin to keep BP high still, so we might also give an ACE inhibitor)