Antihypertensives Flashcards
3 main factors affecting blood pressure
CO
Blood volume
Resistance
- artery walls flexibility
- artery diameter
- blood viscosity or thickness
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
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
Classes of Antihypertensive meds
ACE inhibitors
ARBs - ACE II receptor blockers
Beta-blockers
Calcium channel blockers
Diuretics
Centrally acting antihypertensives (methyldopa)
Peripheral vasodilators (hydralazine)
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
Ace inhibitor meds
quinapril
lisinopril
enalapril
captropril
fosinopril
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)
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
ACE inhibitors contradictions
pregnancy - teratogenic effects on foetus
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
AT II receptor blocker/ ARB meds
losartan
candesartan
adverse effects of ARBs
Hypotension
Hyperkalaemia
DO NOT CAUSE COUGH as it does not accumulate bradykinin
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
Indicators of beta blockers
HTN
Stable angina
Cardiac dysrhythmias after MI
HF
secondary prevention after MI
Beta blocker meds
Cardioselective Beta-1 blockers:
metoprolol
celiprolol
bisoprolol
Beta and Alpha-1 blockers:
labetalol
carvedilol
sotalol
Adverse effects of Beta blockers
Bradycardia
Bronchospasm
Drowsiness and fatigue
Worsen CHF
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
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
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
CCB meds
3 classes:
Verapamil - myocardium
Nifedipine - smooth muscle
Diltiazem - myocardium & smooth muscle
CCBs indicators
HTN
Angina
Dysrhythmias
CCBs adverse effects
Constipation
Nocturia (waking up during the night and urinate)
Headache (cerebral vasodilation)
Hypotension, postural hypotension and fatigue (risk of falls)
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
