Antihypertensives Flashcards by Rymel Polittude

3 main factors affecting blood pressure

CO
Blood volume
Resistance
- artery walls flexibility
- artery diameter
- blood viscosity or thickness

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Causes of HTN

essential HTN is UNKNOWN

psychological and physiological stress
High Na and low K and Ca - facilitates RAAS increasing BP
metabolic syndrome - obesity, dyslipidaemia, diabetes - mainly affects afterload/SVR since larger body mass (excess fat and sugar) the longer the blood vessels, in response, the heart has to pump harder to get the same amount of pressure getting into the tissues putting a strain in the heart overtime increasing chance of having CADs
smoking - excess vasoconstriction
environmental factors - eg. pollution as air pollutants enter the systemic circulation and causes vasoconstriction
genetic factors

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long-term consequences of HTN

heat performance gets overused leading to several CADs:

Heart failure - when RAAS gets overused causing blood retention in the systemic circulation (pulmonary/ peripheral oedema)
Accelerated atherosclerosis > MI
Renal failure - renal arteries are damaged overtime and narrows causing insufficient bladder perfusion in the kidneys
Stroke - blood vessels in the brain gets damaged
Weakened blood vessel walls > aortic/ cerebral aneurysms

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Classes of Antihypertensive meds

ACE inhibitors
ARBs - ACE II receptor blockers
Beta-blockers
Calcium channel blockers
Diuretics

Centrally acting antihypertensives (methyldopa)
Peripheral vasodilators (hydralazine)

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Pharmacodynamics of ACE inhibitors

inhibits conversion of ACE I to ACE II causing:
decreased vasoconstriction > decreased SVR
decreased aldosterone production > increasing Na+ and H2O excretion
decreased BP
increased renal blood pressure

indications: HTN, heart failure and nephropathy

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Ace inhibitor meds

quinapril
lisinopril
enalapril
captropril
fosinopril

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adverse effects of Ace inhibitors

Hypotension (monitor for orthostatic hypotension and dizziness)
Hyperkalaemia (since aldosterone is inhibited K+ are retained)
Angioedema (blocks airway, swelling underneath the skin)
Cough (ACE inactivates bradykinin - which mediates inflammation causing vasodilation)

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Nursing considerations for Ace inhibitors

monitor hypotension
monitor K+ levels - avoid diet rich in K and Na
assess angiodema (swelling of the face and mouth)
educate NOT TO SUDDENLY STOP ACEIs as it causes REBOUND HTN

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ACE inhibitors contradictions

pregnancy - teratogenic effects on foetus

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Pharmacodynamics of ARBs/ Angiotensin II receptor blockers

Blocks angiotensin II receptors in the smooth muscles of the arteries inhibiting vasoconstriction
High affinity to AT II receptors causing vasodilation
Lowers BP and increase blood volume to the heart

Indicators:
HTN
alternative to ACE inhibitors to manage HF and diabetic nephropathy

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AT II receptor blocker/ ARB meds

losartan
candesartan

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adverse effects of ARBs

Hypotension
Hyperkalaemia

DO NOT CAUSE COUGH as it does not accumulate bradykinin

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Pharmacodynamics of beta-blockers

Antagonist at sympathetic (noradrenaline) beta receptors
Blocks:
alpha-1 receptors: decreased SVR
beta-1 receptors:
- decreased HR and myocardial contractility > reduced myocardial O2 demand
- inhibits renin release > inhibit Na+ and H2O retention > reduce preload and decrease SVR
- slows development of atherosclerotic plaques

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Indicators of beta blockers

HTN
Stable angina
Cardiac dysrhythmias after MI
HF
secondary prevention after MI

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Beta blocker meds

Cardioselective Beta-1 blockers:
metoprolol
celiprolol
bisoprolol

Beta and Alpha-1 blockers:
labetalol
carvedilol
sotalol

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Adverse effects of Beta blockers

Bradycardia
Bronchospasm
Drowsiness and fatigue
Worsen CHF

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Contradictions for beta blockers

Pts with asthma/COPD - beta blockers can block beta-2 receptors in the lungs causing bronchospasm
Pts with DM - beta blockers inhibits beta cells in the pancreas preventing glycogenolysis causing hypoglycaemia

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Nursing considerations for beta blockers

DO NOT STOP ABRUPTLY - risk of rebound HTN, instead decrease dose slowly
monitor hypotension - risk of falling from orthostatic hypotension
educate to change position slowly
monitor S&S of HF - wet lung sounds, weight gain, oedema

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Pharmacodynamics of calcium channel blockers/ CCBs

blocks Ca channels by inhibiting Ca influx into smooth muscles and myocardial cells
- smooth muscle relaxation> vasodilation including coronary blood vessels
- reduce AV conduction
- decrease heart workload

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CCB meds

3 classes:
Verapamil - myocardium
Nifedipine - smooth muscle
Diltiazem - myocardium & smooth muscle

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CCBs indicators

HTN
Angina
Dysrhythmias

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CCBs adverse effects

Constipation
Nocturia (waking up during the night and urinate)
Headache (cerebral vasodilation)
Hypotension, postural hypotension and fatigue (risk of falls)

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Nursing considerations for CCBs

Orthostatic hypotension (risk of falls) - encourage to sit in the side of the bed for few minutes then rise up slowly
Change positions slowly when lying

DO NOT STOP MEDS ABRUPTLY! it can cause rebound HTN/ Angina
DO NOT DRINK GRAPEFRUIT JUICE - can cause severe hypotension
ELEVATE leg to reduce oedema
ENCOURAGE fluids, fruits, and fibre rich diet for CONSTIPATION

Pharmacodynamics of Diuretics

act to reduce Na reabsorption in the kidneys
reduce H20 retention
decrease blood volume and plasma Na

4 main classes of Diuretics

Loop diuretics Thiazide diuretics K sparring diuretics Osmotic diuretics

Pharmacodynamics of Loop diuretics

Acts on loop of henley Inhibit Na+ & Cl- reabsorption (25%) > Na+ loss > decreased reabsorption of H20 > increase UO and decrease blood volume VERY STRONG DIURESIS

Loop diuretic meds

Furosemide

Loop diuretics indicators:

HTN HF or CHF renal disease Pulmonary and Peripheral oedema

Loop diuretics adverse effects

HYPOKALAEMIA - highest risk (< 3 mmol/L) Dehydration Hypotension Hyponatraemia Hyperglycaemia

Nursing considerations for Loop diuretics

obtain and monitor vitals monitor input and ouput Replace K+ if below normal

Pharmacodynamics of Thiazide diuretics

acts on DCT/ distal convoluted tubule inhibit reabsorption of Na+ & Cl- (5%) > decreasing reabsorption of water > increase UO and decrease blood volume LESS DIURESIS compared to Loop diuresis

Thiazide diuretic meds

bendroflumethiazide chlortalidone indapamide

Thiazide diuretics adverse effects

HYPOKALAEMIA - less intense compared to loop diuretics (< 3mmol/L) Hypotension Hyperglycaemia Hyponatraemia Dehydration

Thiazide diuretics indicators

HTN HF renal disease Oedema

Nursing considerations for thiazide diuretics

obtain and monitor vitals monitor input and output replace K+ if levels below normal daily weights AVOID for pts with GOUT AVOID this meds for pts with SULFA ALLERGY

Pharmacodynamics of K+ sparring diuretics

Aldosterone antagonist increase Na+ & H20 excretion > reabsorb K+

K+ sparring diuretic meds

Spironolactone

K+ sparring diuretics indicators

HTN Oedema Hypokalaemia

K+ sparring diuretics adverse effects

HYPERKALAEMIA (> 5 mmol/L) hypotension diarrhoea gastritis drowsiness erectile dysfunction

Nursing considerations for K+ sparring diuretics

AVOID FOODS HIGH IN K monitor K+ levels (risk of hyperkalaemia)

Pharmacodynamics of osmotic diuretics

increase viscosity of the filtrate H20 can’t be reabsorbed increase excretion of Na+ & Cl-

Osmotic diuretics indicators:

Cerebral oedema Decreased intraocular pressure (fluid inside the eyes)

osmotic diuretics adverse effects

Oedema blurred vision N&V, diarrhoea urinary retention

Nursing considerations for osmotic diuretics

IV ONLY! perform neuro assessment and LOC (lvl of consciousness) for cerebral oedema

adverse effects of diuretics to older adults

DEHYDRATION POSTURAL HYPOTENSION ELECTROLYTE IMBALANCES RISK FOR: falls, incontinence, confusion, constipation and fever

what is “triple whammy” when taking antihypertensives

a combination of ACE inhibitors, ARBs, diuretics and NSAIDs

adverse effects of “triple whammy”

decrease renal function

Pharmacodynamics of methyldopa

a prodrug converted into methylnoradrenaline active metabolite that binds to alpha-2 receptors in the brain stem reducing sympathetic stimulation > decrease SVR > slows HR

adverse effects of methyldopa

postural hypotension mental clouding (less wakeful or aware) GI upsets

nursing considerations for methyldopa

AVOID ALCOHOL (increase sedation effects) TAKE IT WITH FOOD if feeling nauseated

Pharmacodynamics of Hydralazine

direct acting vasodilator selective arterioles dilator > decrease SVR > increases HR and myocardial contractility

Hydralazine indicators

HTN (especially for pregnant mothers) HF

hydralazine adverse effects

Tachycardia hypotension fluid retention GI upset headache dizziness

Pharmacodynamics of Glyceryl Trinitrate/ GTN

decreases smooth muscle contractility act mainly on veins and arterioles reduces preload and some afterload > decreases BP

GTN indicators

HTN prior to STEMI and stroke clot retrieval