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55 Cards in this Set
- Front
- Back
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Name three vasodilators
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hydralazine
minoxidil sodium nitroprusside |
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name an alpha1 blocker
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prazosin
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name two adrenergic inhibitors
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guanethidine
reserpine |
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name two alpha2 agonists
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methyldopa
clonidine |
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name a beta-adrenergic antagonist
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propranolol
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name two calcium channel blockers
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amlodipine
verapamil |
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What is the most common form of hypertension
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essential
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a 5-6 mmHg decrease in diastolic pressure reduces the probability of strokes by...
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35-40%
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BP =
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CO x TPR
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CO =
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HR x SV
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what does hydralazine do
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RELAXES ARTERIAL SMOOTH MUSCLE
direct relaxation of arterial vascular smooth muscle with little effect on venous and capacitance vessels |
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what is a serious adverse effect of hydralazine
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baroreceptor reflex mediated stimulation of the sympathetic nervous system evoked by the vasodilation and decreased BP -> inc heart rate, contractility, plasma renin and fluid retention
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what can the increased contractility and oxygen demand of the heart in response to the baroreceptor reflex of hydralazine cause
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cardiac ischemia --> CONTRAINDICATED in patients with CAD and patients over 40
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What is given to minimize the adverse effects of hydralazine
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sympatholytic agents
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when is hydralazine most often used
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oral antihypertensive during pregnancy
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what does minoxidil do?
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nothing, first it has to be metabolized to minoxidil sulfate
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what does minoxidil sulfate do
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activates the ATP-modulated potassium channel in ARTERIOLE smooth muscle --> hyperpolarization and relaxation with little effect on venous and capacitance vessels
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what is an adverse effect of minoxidil
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reflex barorecept increase in heart rate, contractility, plasma renin and fluid retention which counteracts the antihypertensive effect of minoxidil
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as with hydralazine, what can the increased contractility and oxygen demand in the heart after minoxidil administration lead to
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cardiac ischemia --> CONTRAINDICATED in patients with CAD and ventricular hypertrophy
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what is coadministered with minoxidil to minimize adverse effects
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sympatholytic agents (beta antagonists)
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What occurs with topical minoxidil treatment
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hair growth --> Rogaine
**can still have measurable cardiovascular effects in some people |
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what does sodium nitroprusside do?
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nothing, it has to be activated to nitric oxide
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what does nitric oxide do
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activates guanylate cyclase-> cGMP -> activates GMP dependent myosin light chain phosphatase -> dephosphorylates myosin light chain -> decreased contractile state of smooth muscle -> vasodilation in ARTERIOLES and VENULES
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why must sodium nitroprusside be given by continuous IV infusion
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it is unstable and decomposes when exposed to light
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what does prazosin do
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alpha blocker - reduces arterial resistance and venous capacitance by inhibiting the vasoconstriction induced by endogenous catecholamines
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what is the major adverse effect of alpha blockers like prazosin
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first dose phenomenon = orthostatic hypotension in ~50% of patients
- most likely to occur if patients are taking beta antagonists or diuretics |
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are alpha blockers like prazosin typically effective as a sole treatment for hypertension
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no- they typically evoke Na and water retention
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what does guanethidine do
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inhibits adrenergic function- inhibits PERIPHERAL postganglionic adrenergic neurons -> concentrated within the neurosecretory vesicles where it replaces and depletes the active transmitter norepinephrine
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what are the adverse effects of guanethidine due to
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sympathetic dysfunction- postural hypotension, sexual dysfunction, diarrhea
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what does reserpine do
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inhibits adrenergic function- binds to storage vesicles in central and peripheral adrenergic neurons, interferes with a transmitter uptake system and renders vesicles dysfunctional -> nerve endings lose their ability to concentrate and store norepi and dopamine
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what are adverse effects of reserpine
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sedation, and inability to concentrate and severe depression
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what does methyldopa do
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central sympatholytic agent (alpha 2 agonist)- acts centrally to reduce sympathetic activity by depleting neuronal stores of norepi
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what is the metabolism of methyldopa
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converted by adrenergic neurons -> alpha-methyl-dopamine -> alpha-methyl-norepinephrine -> substituted for norepi in secretory vesicle
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when is methyldopa often used
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as an oral antihypertensive during pregnancy
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what does clonidine do
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alpha 2 agonist that reduces the activity of neurons in the brainstem responsible for generating and maintaining sympathetic activity
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what happens in clonidine overdose
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can activate alpha 2 receptors on vascular smooth muscle cells causing vasoconstriction
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name some adverse effects of methyldopa and clonidine
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dizziness, reduced libido, sedation and depression
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what can sudden withdrawal of alpha 2 agonists cause
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withdrawal syndrome with blood pressure rising to levels above those that were present prior to treatment
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how do calcium channel blockers work
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block Ca influx through voltage gated calcium channels in arterial smooth muscle -> prevents Ca from binding calmodulin ->prevents myosin light chain kinase from phosphorylating myosin light chain -> prevents interactions between myosin and actin -> DECREASING vascular resistance and BP
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do calcium channel blockers work on venous smooth muscle
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no, only arterioles
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name two dihydropyridine calcium channel blockers
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nifedipine
amlodipine |
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name a non-dihydropyridine calcium channel blocker
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verapamil
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how do dihydropyridine calcium channel blockers differ from non-dihydropyridine calcium channel blockers
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nifedipine and amlodipine cause baroreceptor reflex increase in sympathetic activity and tachycardia; verapamil reduces BP without evoking tachycardia due to an additional direct negative chronotropic effect
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What is a consequence of the direct arteriole vasodilation of calcium channel blockers
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they may increase venous return -> CONTRAINDICATED in patients with impaired cardiac function such as ventricular hypertrophy, ischemic heart disease, or CAD
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What has nifedipine actually been shown to do
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increase the risk of ischemic heart disease
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in what patient population can long acting calcium channel blockers be well tolerated
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patients with angina and arrhythmia; can be effective monotherapy in low-renin populations (elderly and African-American populations)
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name adverse effects of calcium channel blockers
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cardiac depression
cardiac arrest bradycardia AV block congestive heart failure |
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Nifedipine:
Coronary vasodilation... peripheral vasodilation... HR... Contractility... Rate of recovery of Ca channels... AV conduction... |
Coronary vasodilation...++++
peripheral vasodilation...++++ HR...REFLEX INCREASE Contractility...REFLEX INC Rate of recovery of Ca channels...NO CHANGE AV conduction...NO CHANGE |
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verapamil:
Coronary vasodilation... peripheral vasodilation... HR... Contractility... Rate of recovery of Ca channels... AV conduction... |
Coronary vasodilation...++
peripheral vasodilation...++ HR...DECREASE Contractility...DECREASE Rate of recovery of Ca channels...DECREASE AV conduction...SLOWS |
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what does propranolol do
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a beta adrenergic antagonist- reduces myocardial contractility and cardiac output by blocking any endogenous sympathetic beta1 stimulation of the cardiac SA node and ventricular muscle
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what do beta antagonists like propranolol do to renin and angiotensin II
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reduce renin and decrease angiotensin II
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what is propranolol useful for
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treatment of angina and arrhythmias; may decrease mortality after acute myocardial infarction by about 10%
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what population may have a lesser antihypertensive response to beta andrenergic antagonists like propranolol
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elderly and African Americans
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name adverse effects of propranolol
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erectile dysfunction
depression insomnia |
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in what population is propranolol contraindicated in
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patients with asthma since blocking beta2 receptors can lead to bronchoconstriction
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