4 - RAS & Antihypertensives Flashcards
What does cardiac output depend on?
- Venous return (venous tone, blood volume)
- Heart rate
- Contractility
What does total peripheral resistance depend on?
Resistance vessel diameter (arterial tone)
What are chronic increases in BP normally due to?
Increased arterial resistance (total peripheral resistance)
What is preload?
Venous return
What is afterload?
Arterial resistance
What are some OTC and prescription drugs that can cause high BP?
- Estrogens (oral contraceptives)
- NSAIDs
- Antidepressants, cyclosporin, amphetamines (stimulants)
What are the 3 main compensatory responses to decreased BP? What are causes for this decrease in BP?
1) Decrease renal perfusion pressure and increase sodium retention
2) Increase RAAS, A2, and aldosterone
3) Increase symp nerve activity and norepinephrine
- Causes = hypovalemia (hemorrhage, dehydration), postural, heart failure, antihypertensive
What are some non-pharms for tx of hypertension?
- Sodium restriction
- Weight loss
- Exercise
- Reduced alcohol intake
- Smoking cessation
- Relaxation
What are some first line single agents for hypertension tx?
- ACE inhibitor
- ARB
- Diuretic
- Calcium channel blocker
- Beta-adrenergic receptor antagonist (but not in uncomplicated hypertension)
What is the dose response for lowering BP for diuretics?
Relatively flat, so increasing dose produces little improvement in effect
What problems arise when increasing dose of diuretics?
- Hypokalemia
- Glucose intolerance
- Increased LDL
Loop diuretics are greater _____ but weaker ______ than thiazide diuretics
Greater diuretic but weaker antihypertensive
Are loop diuretics a good choice for long term tx of hypertension?
No, fast onset but short acting
When are potassium sparing diuretics useful for hypertension tx?
- When used w/ thiazides to decrease potassium loss
- When increased BP is due to mineralocorticoid excess
Which drugs are ACE inhibitors?
- Captopril
- Enalapril
What are the functions of ACE inhibitors?
- Decrease A2 levels
- Decrease TPR
- Decrease aldosterone
Which drug is an ARB?
Losartan
What are the functions of ARBs?
- Block A2 receptors
- Decrease TPR
- Decrease aldosterone
ACE inhibitors and ARBs are first line in _____
Hypertension, CHF and/or diabetic nephropathy
Do ACE inhibitors and ARBs cause a reflex increase in cardiac output?
No
What are some possible problems w/ ACE inhibitors and ARBs?
- Rash
- Cough (ACE inhibitors)
- Hyperkalemia
- Proteinuria
- Angioedema
ACE inhibitors and ARBs are recommended for ____ hypertension w/ or w/o a concurrent condition of _____
- Uncomplicated hypertension
- Concurrent condition = heart failure, left ventricle dysfunction, post MI, diabetes, systolic dysfunction, proteinuria
What happens if plasma A2 levels increase while a px is taking ACE inhibitors or ARBs? When might this occur?
- Drastic drop in BP is possible
- Renal artery stenosis, hypovalemia, diuretic use
ACE inhibitors and ARBs are contraindicated in ______
Pregnancy
What is the first line choice for hypertension in pregnancy?
Thiazide diuretic
Low plasma potassium increases _____
Digitalis toxicity
What can decrease plasma potassium?
- Increased aldosterone
- Diuretics
What can increase plasma potassium?
- ACE inhibitors
- Beta receptor blockers
What is the function of calcium channel blockers?
Block L-type calcium channels, one predominantly vascular and the other predominantly cardiac
What are the 2 types of calcium channel blockers and which drugs are in each category?
1) Vascular/dihydropyridines - amlodipine, nifedipine
2) Cardiac and vascular/non-dihydropyridines - verapamil, diltiazem
For dihydropyridines, ___ acting agents are preferred for hypertension
Long
What are dihydropyridines used for?
- Angina
- Raynauds
- Hypertension
- Hypertensive crisis
What effect do diuretics and nidefipine have together?
Diuretics may block nifedipine effects on BP
What are non-diphydropyridines used for?
- Hypertension if also concerned about heart rate control in atrial fibrillation
- Px w/ angina
What is diltiazem used for?
Treat angina and hypertension
What should verapamil should not be used w/ and why?
Beta receptor blocker b/c both block AV node
Verapamil is contraindicated in ______
Heart failure
What is the first line single therapy in uncomplicated hypertension?
Calcium channel blockers
When are calcium channel blockers especially useful for hypertension tx?
- When beta blockers are contraindicated (COPD or diabetes)
- Elderly and African Americans
What are some adverse effects of calcium channel blockers?
- Headache, flushing, edema, constipation
- Increased mortality post MI w/ short acting preparations
Calcium channel blockers can be used to treat hypertension in the presence of what other coexisting conditions?
- Angina pectoris
- Raynaud’s
- Asthma or COPD
What is the mechanism of beta blockers to decrease BP?
Unknown
When are beta blockers best used for hypertension tx?
- As a second drug to block reflex activation of the heart by SNS
- Given for hypertension when concomitant diseases also benefit (post MI, heart failure, angina, glaucoma)
What are some problems w/ beta blockers?
- May increase triglycerides and decrease HDL
- Increased incidence of erectile dysfunction
- Increased incidence of type 2 DM
Which drugs for hypertension protect against stroke?
ACE inhibitors and ARBs
When would beta blockers be used in an asthmatic?
W/ post MI or heart failure
Is prazosin a good single agent to use for chronic BP lowering?
- Alpha 1 antagonist, so vasodilates arteries and veins
- Not effective
What are problems w/ prazosin?
- Fluid retention w/ long term tx (so give w/ diuretic**)
- First dose effect – initial large decrease in BP
- Orthostatic hypotension
What is the dosing for clonidine for hypertension tx?
2 unequal doses, high dose at night
What can rapid cessation of clonidine cause?
Rebound hypertension
Is hydralazine (vasodilator) used alone for chronic BP lowering?
No
What should hydralazine be given w/ for hypertension tx? Why?
- Beta blocker to prevent increase in heart rate and contracility
- Diuretic to increase excretion of water
Can hydralazine be given during pregnancy?
Yes
What are problems w/ hydralazine (vasodilator)?
- May cause lupus-like syndrome
- May increase myocardial stimulation
- Headache, nausea, hypotension, tachycardia, angina pectoris
What is another vasodilator used besides hydralazine?
Minoxidil
What is sodium nitroprusside and what is it used for?
- Venous and arteriolar dilator
- Used for hypertensive encephalopathy
What is the target BP for px under 80 y/o w. uncomplicated hypertension?
140/90 mmHg or less
What is the target BP for px w/ hypertension and other conditions (ex: atherosclerotic CV disease, DM, chronic kidney disease)?
Below 140/90 mmHg
Which agents do younger px w/ hypertension better respond to?
- ACE inhibitors, ARBs, or beta antagonists
- Beta blockers are inferior to protect against stroke
Which agents do black px and elderly px w/ hypertension better respond to?
- Thiazide diuretics or long acting calcium channel blockers
- If px has other indications, may need ACE inhibitor or ARB
