Transcript Drugs used to treat Hypertension

Drugs used to treat
Hypertension
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HTN = BP > 140/90
Assos. With:
premature death
vascular disease of brain, heart,kidneys
Goal of treatment
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Prolong useful life by preventing
cardiovascular problems by reducing
BP < 140/90
Blood Pressure
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Review of physiology
BP caused by: _________
Systolic pressure: __________
Diastolic pressure: __________
Blood Pressure
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Primary Factors
Cardiac output
Peripheral resistance
Blood Volume
Initial tx. of hypertension
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Lifestyle modification first
No smoking
Weight control
Reduce alcohol intake
Decrease stress
Sodium control
Treatment of hypertension
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Lifestyle modification first
Initial tx. drug- diuretic or B-blocker
Low dose first, increase dose if
necessary
2nd med. if needed
Most respond with diuretic and one
other medication (stepped care)
Tx pump, fluid volume, or PVR
Drugs to treat hypertension
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5 primary classes
Diuretics
Calcium channel blockers
Angiotesin converting enzyme (ACE)
inhibitors
Autonomic nervous system agents
Direct acting vasodilators
Diuretics
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Tx: mild to moderate HTN
First drug of tx.
Also tx. heart failure or kidney disease
Few adverse side effects
Used with other antihypertensives to
enhance effectiveness
Diuretics
Action
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Reduce blood volume through urinary
excretion of water and electrolytes
Electrolyte imbalances can occur
(mainly hypokalemia)
Depends on type of diuretic
Diuretics
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Most efficient: Loop or High-ceiling
Reduce edema assos. with CHF
Increase UO even if blood flow to kidney is
diminished
Hypokalemia
KCL supplement given
Lasix, Demadex, Bumex
Diuretics
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Most widely prescribed: Thiazides
Mild to moderate HTN-primarily
Hydrodiuril – hydrochlorothiazide
(HCTZ)
Hypokalemia
Potassium supplement- KCL
Diuretics
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Potassium-sparing:prevent hypokalemia
Mild HTN
Used in combination with other diuretics
No supplement taken
Watch for hyperkalemia
Side effects
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Orthostatic hypotension
Dry mouth,irritation
Report:
Electrolyte imbalance- hypokalemia
(potasium<3.5)
Disorientation
dehydration
Implications for use
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Optimal time to admin.= AM
Check VS
Accurate intake and output
Daily weights
Monitor electrolyte imbalances
Calcium Channel Blockers
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Emerged as major drug to tx. HTN
Used for arrythmias also
Alternative to B-blocker (hx. Asthma)
Calcium Channel Blockers
Action:
blocks ca+ access to muscle cells
contractility +
conductivity of the
______________________
demand for oxygen
PVR (relaxing arterioles)
Calcium Channel Blockers
Examples
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Verapamil
Very
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Procardia (nifedipine)-HTN
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Cardizem (diltiazem)-arrythmias Drugs
Nice
Calcium Channel Blockers
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SIDE EFFECTS
BP
Bradycardia
May precipitate A-V block
Headache
Abdominal discomfort
Peripheral edema
Angiotensin-Converting
Enzyme Inhibitors
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“ACE” inhibitors
Mainstay of oral vasodilator therapy
Major breakthrough in tx. of HTN
More effective when used with diuretics
ACE INHIBITORS
Angiotensin
Converting
Enzyme (ends in PRIL)
captopril
(Capoten)
enalapril
(Vasotec)
benzapril
(Lotensin)
RENIN-ANGIOTENSINALDOSTERONE AXN.
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BP
excrete renin
formation of angiotensin I
angiotensin II = potent vasodilator
Aldosterone release
Na and H2O
ACE INHIBITORS
ACTION
peripheral vascular resistanse without
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cardiac output
cardiac rate
cardiac contractility
Advantages
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Infrequent orthostatic hypotension
Lack of aggravation of pulmonary dx.
Lack of aggravation with DM
Increase renal blood flow
Side effects
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Headache
Orthostatic hypotension-infrequent
Cough
GI distress
Drug interactions
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Diuretics
Alcohol
Beta-blockers
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All the above enhance the effects
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Adrenergic Receptors
Review of ANS
Sympathetic Nervous System
Alpha 1 = vasoconstriction
Alpha 2 = feedback/vasodilation
Beta 1 = increases heart rate
Beta 2 = bronchodilation
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Beta Adrenergic Blocking
Agents
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Known as Beta-blockers
Axn: Inhibit cardiac response to
sympathetic nerve stimulation by
blocking Beta receptors
Decreases heart rate and C.O.
Decreases blood pressure
Beta Adrenergic Blocking
Agents
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Examples – “olol” names
Beta 1: Atenolol
Beta 1 and 2: Propranolol
Nursing Implications
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Can not be abruptly discontinued
Check baseline b.p.
Check hx. of resp. condition-aggravates
bronchoconstriction
Side effects
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Bradycardia
Bronchospasm, wheezing
Diabetic: hypoglycemia
Heart failure: edema,dyspnea,rhales
Interactions
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Antihypertensives- additive effect
B-adrenergic agents- inhibit axn.
Enzyme inducing agents-enhance
metabolism
Indomethacin and salicylates:< controll
Alpha-1 adrenergic blockers
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Alternative if B-blockers and diuretics
do not work
Also used to tx. mild to mod. urinary
obstructive dx. (BPH)
Alpha-1 Adrenergic Blocking
Agents
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Action:
Block postsynaptic alpha-1 adrenergic
receptors to produce arteriolar and
venous vasodilation
Reduces peripheral-vascular resistance
Side effects
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Drowsiness
Headache
Dizziness,tachycardia,fainting
Weakness,lethargy
Interactions: other antihypertensives
(enhance effects)
Clinical Implications
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Side effects most prevalent with first
dose
Warn pt. that this is nl.
Instruct pt. to lie down if
dizzy,weak,etc.
Examples of Apha-1 blockers
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Cardura (doxizosin)
Minipress (prazosin)
Hytrin (terazosin)
Centrally Acting Alpha-2
Agonists
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Stimulate Alpha-2 receptors in
brainstem
Decreases HR, SBP and DBP
More frequent side effects –
drowsiness, dry mouth, dizziness
Never suddenly DC = rebound HTN
Clonidine – Catapres ( available in TTS)
Methyldopa - Aldomet
Direct Acting Vasodilators
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Action: dirct arteriolar smooth muscle
relaxation, decreasing PVR
Uses: HTN, renal dx., toxemia of
pregnancy
Ex: Apresoline, Minoxidel
SE: tachycardia, orthostatic
hypotension,dizziness, palpitations,
nausea, nasal congestion
Client Teaching for
Antihypertensive drugs
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Take medication as prescribed
Never discontinue without approval of
healthcare provider
Incorporate lifestyle changes, even if
medication brings BP within nl. Limits
Check BP on regular basis and report
significant variations (and pulse)
Get out of bed slowly
Client Teaching for
Antihypertensive drugs
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Increase intake of potassium-rich foods,
unless taking potassium sparing
diuretics
Weigh regularly and report abnormal
weight gains or losses
Do not take OTC drugs without
checking with healthcare provider