DRUGS FOR HYPERTENSION Flashcards
how many Canadian adults have hypertension?
1 in 4
what is the most prevalent risk for cardiovascular disease?
hypertension
what are common risk factors for hypertension?
diabetes mellitus, chronic kidney disease, diet and sedentary behaviour
primary “essential” hypertension
- most common
- no known cause - represents 90-95% of cases
- asscociated with genetic predisposition, dietary salt intake, adrenergic tone
secondary hypertension
- disease/condition causes BP rise
- known cause - represents 5-10% of cases
- examples: pheochromocytoma, adrenal cortical tumours, drugs
are most patients symptomatic or asymptomatic?
asymptomatic
what are physiological effects of hypertension?
- prolonged force on vessels thicken muscles in the arterial system; reduced responsiveness
- heart constantly works harder to expel blood against a greater force, increasing the workload of the heart; left ventricle thickens
- increased force damages inner lining of arteries; susceptible to atherosclerosis and narrowing of the vessel lumen
- microvascular damage leading to losses in vision, kidney and cerebral function
what diseases can occur from hypertension?
cerebrovascular disease, coronary artery disease, GHF, cardiac death, renal failure, peripheral vascular disease, dementia
what is blood volume driven by?
fluid loss
- dehydration
fluid retention
- aldosterone
- ADH
what is peripheral resistance/diameter of arterioles driven by?
- sympathetic nervous system activity
- renin/angiotensin II
- increase in blood viscosity
what is cardiac output driven by?
stroke volume
- preload
-contractility
- after load
heart rate
- SNS
- parasympathetic nervous system
- epinephrine
what is automated office BP?
referes to multiple BP readings (3-6) with a fully automated sphygmomanometer with the pt resting done quietly.
- eliminates the white coat effect and provides readings which are more accurate/similar to the awake ambulatory BP and home BP
what is ambulatory BP monitoring (ABPM)?
worn by the pt for a 24 hour period. measurements taken at 20-to-30 minute intervals
lifestyle recommendations for hypertension
- reduce sodium intake (2000 mg/day) (water follows salt which raises BP)
- smoking cessaton
- abstaining from alcohol or reducing it
- maintenance of weight and waist circumference
- physical exercise 30-60 min of moderate intensity, 4-7 days a week
- healthy diet, low in saturated fats and cholesterol, high in veggies an fruit, protein from plant sources, low fat dietary products, whole grain food rich in dietary fibre
- stress management/ relaxation therapies
what are the 6 drug classes that can be used to reduce BP?
- thiazide/thiazide-like diuretic
- ACE-I
- ARB
- long acting CCB
- B blocker
- single pill combination
what are the two renin angiotensin system (RAS) drug classes?
ACE-1, ARB
Thiazide an thiazide-like diuretics
- first line therapy for the management of hypertension
- reduce stroke volume (block sodium/chloride transporter in the distal tubule, facilitating the urinary excretion of electrolytes (Na, K, Cl, Ca) an water, thereby reducing blood volume
- should be used with caution in pt with renal disease, diabetes, gout, liver disease, hyperlipidemia
- administer during the day to prevent nocturia
what are adverse effects of Thiazide an thiazide-like diuretics?
- GI upset, orthostatic hypotension, hyperglycaemia
, fluid an electrolyte imbalance (hypokalemia; potassium-rich diet or potassium sparing diuretic)
what drug should you give a patient experiences hypokalemia?
you can give them a potassium diuretic
drug drug interactions (hypertension)
lithium (mood stabilizer), NSAIDS (hold onto water), anti diabetic drugs (hyperglycaemic effects)
what should be monitored when starting diuretic therapy?
sodium an potassium levels, kidney function and BP in first 4-6 weeks
- pt should monitor fluid output and weight gain/loss, report dizziness and light headedness
renin-angiotensin-aldosterone system
renin; released in response to decreased BP
- angiotensin II; very potent, encourages body to conserve H2O
^it increases BP by 1) increasing peripheral resistance in the vasculature and 2) stimulating secretion of aldosterone and ADH
^increases sodium an water retention
- ADH increases water reabsorption
when RAAS inhibited, what is decreased?
TPR and blood volume; reducing BP
angiotensin converting enzyme (ACE) inhibitors
- decrease peripheral resistance and decrease blood volume
- block conversion of angiotensin I to angiotensin II
- increase production of vasodilatory kinins
- inhibit aldosterone secretion
what should be cautioned with angiotensin converting enzyme (ACE) inhibitors?
- CONTRAINDICTATED IN PREGNANCY
- use caution with potassium-sparing diuretics and supplements
- decreased antihypertensive activity with NSAIDS
adverse effects of angiotensin converting enzyme (ACE) inhibitors
- persistent dry cough (up to 30%)
- can cause hyperkalemia
- GI irritation and constipation
- first dose phenomenon, sudden drop in BP, tachycardia
- allergic reaction of lips, mouth an throat, occurring during first month of admin, medical emergency (more common in black ppl)
angiotensin II receptor blockers (ARBs)
- decrease peripheral resistance and decrease blood volume
- block angiotensin II (AT) receptors in arteriolar smooth muscle and in adrenal cortex
- inhibit release of aldosterone
- no effect on bradykinin (lower incidence of cough)
how are ARBs and ACE inhibitors the same?
- ARBs have similar adverse effects and drug drug interactions as ACE inhibitors
- contraindicated in pregnancy
-although ARBS are commonly prescribed to pt who cannot tolerate adverse effects of ACE inhibitors
calcium channel blockers
- block calcium ion channels
- relax vascular smooth muscle, decreasing peripheral resistance
- slows HR, receding cardiac output and cardiac workload
when should calcium channel blockers be used with caution?
in those with liver an kidney impairment
what ate adverse effects of calcium channel blockers?
dizziness, light headedness, fatigue, (hypertension and reflex tachycardia), flushing, nausea
- avoid grapefruit juice - increases serum CCB levels
beta blockers
- sympathetic division of the autonomic nervous system (SANS) increases heart rate and smooth muscle contraction of arterial walls
- alpha 1 receptors
- cardio selective B1 receptor antagonists
- non selective B1 & B2 receptor antagonists
- blocks effect of norepinephrine on arterioles
- block action of NE and E on cardiac muscle reducing speed and force of contraction (HR)
- decrease renin secretion by the kidneys, reducing the production of angiotensin I and decreasing TPR
when are beta blockers most effective?
in patients under the age of 60 with concomitant cardiovascular conditions
- previous history of MI, angina
- reduction in heart rate my cause fatigue & activity intolerance
when should beta adrenergic antagonists be used with caution?
diabetes, depression, Asthma, COPD (use cardio selective drugs only)
