Lecture 5 - pharmacology of the medicines used in Hypertension treatment Flashcards
what is the first and second line treatment of hypertension?
- lifestyle modification
- weight reduction, regular exercises, DASH eating plan, reduction of dietary sodium intake, moderation of alcohol intake - pharmacologic treatment
what drugs are used in the pharmacologic treatment of HTN?
diuretics
sympatholytics - opposes downstream effects of postganglionic nerve firing in effector organs innervated by the sympathetic nervous system. they are indicated for various functions: for example they may be used as antihypertension
at on RAAS
- calcium channel blockers
- direct - acting vasodilators
what drugs are recommended for initial therapy in heart failure?
diuretics
beta blockers
ace inhibitors
angiotensin receptor blockers
aldosterone antagonists
what drugs are used for initial therapy in post MI ?
beta blocker
ace inhibitor
aldosterone antagonist
what drugs are used in the itnitla treatment for coronary artery disease risk?
diuretic
beta blocker
ace inhibitor
arb
ccb
what drugs are used in the initial therapy of diabetes?
diuretics
beta blockers
ace inhibitors
arb
ccb
what drugs are used in initial therapy for chronic kidney disease?
ace inhibitor
arb
what drugs are used in the initial treatment for recurrent stroke prevention?
diuretic
ace inhibitor
what do diuretics do?
all diuretics indirectly prevents the reabsorption of water in kings, most of them by preventing sodium reabsorption
what are the classes of diuretics?
loop diuretics - furosemide supplemented with spirinolactone or amiloride
thiazides - bendroflumethiazide
potassium sparing diuretics - not acting on sodium channels
describe the mechanism of action of loop diuretics
Loop diuretics inhibit the Na+/ K+/ 2CL- co transporter. It prevents the reabsorption of Na+, K+ and 2Cl- from the lumen into the loop of hence
major problem associated with loop diuretics is hypokalaemia
describe the mechanism of action of thiazides
thiazides work by inhibiting the sodium cotransporter in the distal tubule
because this transporter only reabsorbs 5% of the filtered sodium, the are less efficacious than loop diuretics which produces natriuresis and diuresis
describe the mechanism of action of potassium sparing diuretics
potassium sparing diuretics act by inhibiting the Na+ channel in the distal tubule
–> tubule and collecting duct (distal nephron)
potassium sparing diuretics are also known as aldosterone receptor antagonists
what drugs causes renin inhibition?
B1 antagonists she as Aliskiren
not deemed suitable use in the UK
where do ace inhibitors work in the body and give example of ace inhibitor drugs
work primarily in the lung
examples are ramipril, captopril, lisinopril, and enalapril
describe the mechanism of action of ace inhibitors and what effect this has in the body
ace inhibitors block the action of the ace, to prevent the concession form angiotensin I to angiotensin II
a vasoconstrictor and stimulates aldosterone secretion
blocking its action reduces peripheral vascular resistance (afterload), which lowers blood pressure
dilates the efferent glomerular arterial which reduces intra-glomerular pressure
what effect does reducing aldosterone level in the body have?
reducing aldosterone level promotes sodium and water excretion. this can help to reduce venous return (preload), which has a beneficial effect in heart failure
describe the mechanism of action of ARBs and give examples of them
ARBs have a similar effects of ACE inhibitors but instead of inhibiting the conversion of angiotensin I to angiotensin II, ARBs block the action of the AT1 receptor.
examples of ARBs candesartan, valsartan and losartan
describe the mechanism of action of aldosterone antagonists and examples of them
aldosterone antagonists competitively inhibit the aldosterone receptor.
they promote the secretion of Na+ and water excretion from the collecting tubule and duct
also known as potassium sparing diuretics
examples are spironolactone and eplerenone
give an outline of sympatholytics
beta blockers
alpha 1 blockers
alpha/ beta blockers
centrally acting alpha-2 agonists (inhibit the release of norepinephrine)
ganglionic verve
what are beta blocker used in?
used mainly as hypertension treatment
what are the actions of beta blockers in hypertension?
blockade of cardiac beta1 receptors which cause a decrease in heart rate and contractility, and so decrease in cardiac output
improve efficiency
suppress tachycardia causing vasoconstriction
blockade of beta1 receptors in JG cells in the kidney –> decrease in renin release and decrease in RAAS mediated vasoconstriction (angiotensin II) and decrease in volume expansion (aldosterone)
long term use leads to a decrease in peripheral vascular resistance
Describe the beta blockers affinity for receptors
some block both beta 1 and beta 2 receptors - non selective
some have greater affinity for beta-1 than beta-2 - cardioselective - but selectivity is not absolute
some are partial agonists - the are said to have intrinsic sympathomimetic activity
what are the calcium channel blocker dihydropeptides?
amlodipine and nifedipine
