Cardio: Drugs affecting BP Flashcards
What effect does nitric oxide have on blood vessels?
Vasodilation
Organic nitrates mimic the effect of nitric oxide produced by endothelial cells. What is their effect at low dose?
Venorelaxation
Decrease preload
Decrease SV
No change in BP
What is the effect of organic nitrates at high dose?
Arteriolar dilation
Decrease arterial pressure
Reduce after load
Give an example of a short acting nitrate
GTN
How is GTN administered?
Sublingually or IV infusion to avoid first pass metabolism
Give an example of a long acting nitrate
Isosorbide mononitrate
How is isosorbide mononitrate administered?
Orally- resistant to first pass metabolism
What might repeated administration of nitrates result in?
Tolerance (decrease in effectiveness)
What are some of the side effects of nitrates?
Headaches
Postural hypotension
Why are nitrates useful in angina?
They redirect blood towards the ischaemic zone
Which drugs can be used in the treatment of pulmonary hypertension?
Endothelin antagonists (Endothelin released from endothelial cells in response to excess vasodilation causes vasoconstriction of pulmonary arteries)
Give examples of endothelin antagonists
Bosentan
Ambrisentan
What do ACE inhibitors block?
The conversion of angiotensin I to angiotensin II
ACEi’s inactivate bradykinin metabolism, causing it to build up. What is the adverse effect of this?
Dry cough
What do ACEi’s end in?
‘pril’
e.g. lisinopril
ACEi’s are first line in the treatment of what condition in caucasian patients under 55?
hypertension
In which condition is use of ACEi’s contraindicated?
Renal artery stenosis
What effects do ACEi’s have on the heart?
Decrease preload and after load - decrease BP
What conditions are ACEi’s used to treat?
Hypertension
Heart failure
Post MI prophylaxis
What do ARBs block?
Block the agonist action of angiotensin II at angiotensin I receptors in a competitive manner
What do ARBs end in?
‘Sartan’
e.g losartan
When might an ARB be used instead of an ACEi?
If a patient has a dry cough
ARBs do not inhibit bradykinin metabolism
Which drug acts as a potassium channel openers?
Nicorandil
What is nicorandil used to treat?
Angina
Last resort for hypertension
What is the main side effect of nicorandil?
Mouth ulcers
How do alpha1 adrenoceptor antagonists lower MABP?
Cause vasodilation by blocking vascular alpha1 receptors- reduced sympathetic transmission results in decreased MABP
What to alpha1 adrenoceptor antagonists end in?
‘Zosin’
e.g. prazosin, doxazosin
Alpha1 adrenoceptor antagonists are particularly useful in patients with hypertension and what other condition?
Benign prostatic hyperplasia
What is the main adverse effect of alpha1 adrenoceptor antagonists?
Postural hypotension
How do diuretics work to lower BP?
They promote salt (NaCl) + water excretion by inhibiting reabsorption
Where in the kidney do thiazide diuretics act on? Give an example of a thiazide diuretic
Distal tubule
Bendroflumethiazide
Where in the kidney do loop diuretics act on? Give an example of a loop diuretic
Loop of Henle
Furosemide
What are the clinical uses of diuretics?
Thiazide- Hypertension + mild HF
Loop- acute pulmonary oedema + Chronic HF
What are the 4 main side effects of diuretics?
Hypokalaemia
Hyperglycaemia
Increased uric acid (gout)
Impotence
Which drug is known as a ‘potassium sparing diuretic’
Spironolactone
Which receptor does spironolactone block?
Aldosterone receptor (antagonist)
When is spironolactone used?
Moderate- severe heart failure
What is the main side effect of spironolactone?
Gynaecomastia
Which drug acts as a renin inhibitor?
Aliskiren
What is aliskiren used to treat?
Hypertension
