Drugs Affecting Blood Pressure
Terms
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- Blood Pressure (BP)
- cardiac output x peripheral resistance
- Cardiac Output (CO)
- Affected by HR, contractility, venous return and blood volume
- Peripheral Resistance (PR)
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Determined by diameter and length of vessel
Arteriolar constriction - Types of Hypertension
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Primary (Essential) Hypertension - No identifiable cause
Secondary Hypertension - Identifiable cause
Renal disease
Oral contraceptive use
Renovascular disease
Cushings syndrome
Pheochromocytoma - Consequences of Hypertension
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Myocardial Infarction
Heart failure
Angina
Kidney disease
Stroke
Degree of injury related to degree of elevation/higher pressure higher risk
Asymptomatic until long after injury has developed - Benefits of Lowering BP
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↓ morbidity
↑ lifespan
↓ incidence of stroke
↓ incidence of MI
↓ incidence of heart failure - What are some identifiable causes of hypertension?
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Cushings
Pheochromocytoma
Oral contraceptives - Factors that increase CV risk
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Target organ damage
Major CV risk factors
Cigarettes
Obesity
Diabetes
↓exercise - Goals of treatment of hypertension
- ↓ CV and renal morbidity and mortality without ↓ quality of life
- Therapeutic Interventions for hypertension
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Healthy lifestyle changes
Antihypertensive drugs - Classes of Antihypertensive Drugs
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Diuretics
Sympatholytics (Adrenergic Antagonists)- Beta-adrenergic blockers, Alpha 1 Blockers, Alpha/Beta Blockers, Centrally Acting Alpha2, Agonist
Others - ACE Inhibitors, Angiotensin Receptor Blockers (ARB’s), Calcium Channel Blockers, Direct Acting Vasodilators - Sympatholytics (Adrenergic Antagonists)
- Alpha 1, Alpha 2, Beta 1, Beta 2
- Alpha 1 Sympatholytics (Adrenergic Antagonists)
- Eye, arterioles of skin viscera and mucus membranes, veins, male sex organs, bladder neck and prostatic capsule
- Alpha 2 Sympatholytics (Adrenergic Antagonists)
- Presynaptic nerve terminals
- Beta 1 Sympatholytics (Adrenergic Antagonists)
- Heart, kidneys
- Beta 2 Sympatholytics (Adrenergic Antagonists)
- Arterioles of heart, lungs and skeletal muscle, bronchi, uterus, liver, skeletal muscle
- Actions of Beta Blockers
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Block the sympathetic nervous system
Beta adrenergic receptors
↓ HR
↓ force of contraction
Slows conduction through the AV node - Therapeutic Uses of Beta Blockers
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Angina Pectoris
HTN
Cardiac dysrhythmias
MI
Heart failure - Adverse Effects of Beta Blockers
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Bradycardia
↓ cardiac output
Precipitation of heart failure
AV heart block
Reflex tachycardia
Bronchoconstriction inhibition of glycogenolysis - Beta Blockers
- Propranolol (Inderal), Metoprolol (Lopressor)
- Action of Propranolol (Inderal)
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Nonselective beta adrenergic antagonist (Beta1 and beta2)
↓ HR, ↓force of ventricular contraction and slow impulse conduction through the AV node, supress secretion of renin (Beta1)
Bronchoconstriction, vasoconstriction, inhibitions of glycogenolysis (Beta 2)
Lipid soluble – easily crosses membranes
Well absorbed
Widely distributed
Hepatic metabolism
Excreted in the urine - Drug interactions with Propranolol (Inderal)
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Calcium channel blockers
Insulin - Action of Metoprolol (Lopressor)
- Cardioselective (Beta 1 only)
- Therapeutic uses of Metoprolol (Lopressor)
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HTN, heart failure and MI, Hepatic metabolism
Renal excretion - Adverse Effects of Metoprolol (Lopressor)
- Bradycardia, ↓ CO, AV block, rebound tachycardia with abrupt discontinuation
- Action of Alpha blockers
- Block alpha receptors on blood vessels
- Therapeutic Uses of Alpha blockers
- Essential Hypertension
- Adverse effects of Alpha blockers
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Orthostatic Hypertension
Reflex tachycardia
Nasal congestion
Inhibition of ejaculation - Alpha blockers Drugs
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Prazosin (Minipress)
Terazosin (Hytrin)
Doxazosin (Cardura) - Action of Alpha/Beta blocker - Labetolol (Normodyne)
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Blocks beta 1 and beta 2 and selective alpha 1
Alpha blocking cause peripheral vasodilation
Beta blocking prevents reflex tachycardia - Action of Centrally Acting Alpha Agonists - Clonidine (Catapres)
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Inhibits sympathetic nervous system response and reduces sympathetic outflow from the CNS
↓ HR, BP,vasocinstriction and vascular resistance
Severe rebound HTN if discontinued - Action of Centrally Acting Alpha Agonists - Methyldopa (Aldomet)
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Displaces norepinephrine form storage sites
Drug of choice for pregnant women withHTN - renin-angiotensin-aldosterone system
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Hypothalamus - pituitary gland - renin -
Angiotensin I -
Little biologic activity
Angiotensin II
Vasoconstriction
Release of aldosterone
Alteration of cardiac and vascular structure -
Action of ACE Inhibitors -
Captopril (Capoten) -
Blocks the conversion of angiotensin I to angiotensin II
Prevents Na and H20 retention
Decreases peripheral vascular resistance - Significant adverse effects of ACE Inhibitors
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Cough
Hyperkalemia
First dose hypotension
Renal failure
Angioedema
ACE Inhibitors contraindicated in 2nd and 3rd trimesters - ACE Inhibitors - Enalapril
- is the only ACE inhibitor that can be given IV.
- Action of Angiotensin II Receptor Antagonists (ARB) - Losartan (Cozaar)
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Prevents angiotensin II from binding to receptors in many tissues, thus blocking the vasoconstricting and aldosterone-secreting effects of angiotensin II
Decreases peripheral vascular resistance
Does not cause†ACE cough†or hyperkalemia
Angioedema is common
ARB’s contraindicated in 2nd and 3rd trimesters - Action of Calcium Antagonists - (Calcium Channel Blockers )
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Prevent calcium from entering the cells
Treatment of HTN, angina, and cardiac dysrhythmias -
Action of Calcium Channel Blockers -
Verapamil (Calan) -
Blocks Ca channels in blood vessels and in the heart
Essential HTN, angina, and cardiac dysrhythmias - Direct effects of Calcium Channel Blockers
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↓arterial pressure
↓HR
↓AV nodal conduction
↓force of contraction
↑coronary perfusion
Reflex responses - Indirect effects of Calcium Channel Blockers
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Barroreceptor activated
Increased firing of sympathetic nerves to the heart
Direct and indirect negate each other
Drug interactions with Beta blockers -
Action of Calcium Antagonists -
Diltiazem (Cardizem) -
Inhibits calcium ion influx, reduce afterload
Inhibit coronary artery spasm -
Action of Calcium Antagonists -
Nifedipine (ProcardiaXL, Adalat) -
Inhibits calcium ion influx
Vasodilating effects on coronary and peripheral arterioles
Does not slow AV node conduction but can cause cardiosuppression in toxic doses - Adverse effects of Nifedipine (ProcardiaXL, Adalat)
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Flushing
Dizziness
Reflex tachycardia - Common adverse effects for oral preparations of Calcium Antagonists
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GI: constipation, nausea
CV: HA dizziness - What nursing interventions should be done with Calcium Antagonists
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Monitor and treat adverse effects supportively
Overdose: IV calcium chloride or calcium gluconate -
What are the actions of Direct-acting vasodilators -
Hydralazine (Apresoline) -
↓Peripheral resistance
Adjunct with other antihypertensives
Used with beta blockers or clonidine to prevent reflex tachycardia from vasodilation
With diuretics to offset fluid retention from ↑ production of angiotensin II -
What is the adverse effect of Direct-acting vasodilators -
Hydralazine (Apresoline) - Lupus like syndrome
- What are the actions and nursing interventions of Direct-acting vasodilators - Nitorprusside (Nitorpress)
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Used to treat hypertensive crisis (DBP>120)
Directly relaxes vascular smooth muscle
Dilates veins more than arteries
↓ preload and afterload
↓ BP dramatically
IV use only
MUST use a pump
Protect form light
Monitor BP often - What drugs are used in Treatment of Hypotension
- Vasopressors
- What is the Prototype agent of Vasopressors?
- dopamine (Intropin)
- Adverse effects of dopamine (Intropin)
- CV system effects
- What are the actions of dopamine
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Catecholamine and a precursor to NE
Vasopressor used in treating shock
Stimulation of alph-1, beta-1 and dopamine receptors is dose dependent - What are the nursing interventions for dopamine
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IV administration only in acute care settings
Invasive monitoring, pump
Weight based dosing
IMPORTANT
Correct hypovolemia first - What are the contraindications for dopamine
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Pheochromocytoma
Uncorrected tachyarrhythmias
V-fib