Antihypertensive Drugs Flashcards
Why treat hypertension?
Very common, >50% of elderly, major risk factor for stroke and ischaemic heart disease e.g MI
At what point do you treat HTN?
When systolic is over 160 or diastolic is over 100.
What is the equation for blood pressure?
BP = CO X TPR
What do diuretics do?
Act on kidneys to increase diuresis. Increase sodium excretion. Water loss follows and so plasma volume is decreased - decrease in TPR and CO.
What is the site of action for thiazide diuretics?
Distal convoluted tubule in the kidneys.
What is the action of thiazide diuretics?
Inhibit sodium and chloride co-transport. Increase renin release.
What are examples of thiazide diuretics?
Chlorothiazide, Hydrochlorthiazde, Bendrofluazide. Chlorthalidone, Metolazone.
What are the adverse effects of thiazide diuretics?
More frequent urination, high safety, low profile side effects.
What is the site of action for loop diuretics?
Loop of Henle in the kidneys.
When are loop diuretics used?
Very potent. Reserved for patients with renal insufficiency, resistant HTN or heart failure.
What are examples of loop diuretics?
Furosemide, Bumetanide.
What are the 3 classes of vasodilator drugs?
Calcium antagonists, A-Blockers, Angiotensin Antagonists.
What are the actions of vasodilator drugs?
Acts directly on the smooth muscle cells of arteries and arterioles. Lowers the intracellular calcium concentration which causes muscle cell relaxation. Results in vasodilation.
What do Calcium Antagonists do?
Block calcium entry through voltage operated calcium channels in arterial smooth muscle cells.
What are Nifedipine, Amlodipine and Nicardipine examples of?
Calcium antagonists - Dihydropyridines.
What are the side effects of calcium antagonists?
Flushing and ankle oedema.
What do A-Blockers do?
Drugs used for HTN are selective blockers of a1-adrenoreceptors. Prevent vasoconstrictors action of noradrenaline.
What are the examples of A-blockers?
Doxazosin, Terazosin, Prazosin.
What are the adverse effects of a-blockers?
Postural hypotension - dizziness, light headedness. Possible severe hypotension after first does but generally well tolerated.
Give 2 examples of beta blockers.
Atenolol, Metoprolol.
What do B-Blockers do?
Bind to and block B1-adrenoreceptors in the heart. Block action of noradrenaline. Initial effect = decrease rate and force of heart beat and decrease CO.
What are the adverse effects of B-blockers?
Cold hands, Fatigue. Can provoke asthma attacks. Heart failure.
Give example of ACE inhibitors.
Enalapril, Captopril, Lisinopril, Ramipril.
What do ACE inhibitors do?
Prevent conversion of Angiotensin I into Angiotensin II. Causes vasodilation. Decreases plasma volume.
What are the adverse effects of ACE inhibitors?
Dry cough, hypotension.
Give examples of angiotensin II receptor antagonists.
Losartan, Candesartan, Eprosartan, Valsartan
What do angiotensin antags do?
Block the action of angiotensin II at its receptors - causing vasodilation. Used in combination or as an alternative to ACE inhibitors.
What are the side effects of angiotensin antags?
Headache, dizziness.
