Antihypertensive Drugs Flashcards
How is blood pressure regulated? (physiologically)
Sympathetic Nervous system –> inc cardiac output, Beta-1 activation
Kidneys
vasoactive substances produced in blood vessel wall (NO, prostacyclin, aldosterone, etc.)
What influences PVR?
Alpha-1 adrenoceptor stimulation = vasoconstriction
Vasopressin, Angiotensin (AT) II, Aldosterone = vasoconstriction
Locally released substances = adenosine, serotonin, endothelin, prostaglandins
What are the categories of antihypertensives?
Reduce PVR = vasodilators (inc NO), alpha-1 blockers, AT receptor blockers, centrally acting sympatholytic, ACE inhibitors,
Reduce CO = Beta1-adrenoceptor blockers
Target Na secretion and dec BV = Diuretics
What suffix helps identify ACE inhibitors?
-pril
What suffix helps identify ARBs?
-sartan
What is the MOA of ACE inhibitors?
Block the conversion of angiotensin I to angiotensin II through inhibition of angiotensin converting enzyme.
Also inhibit bradykinin
List the relevant ACE inhibitors
Captopril, enalapril, fosinopril, lisinopril, perindopril, ramipril
What effects (NOT ADRs) will ACE inhibitors have?
Reduce AT-II induced vasoconstriction, Na retention, aldosterone release
Reduce effect of AT-II on sympathetic NS activity and growth factor
Cause accumulation of bradykinin
Name and explain some ADRs of ACE inhibitors
Dry cough = due to bradykinin inhibition, irritating the airways and causing vasodilation
Hypotension, headache, dizziness = drop in blood pressure
Hyperkalaemia = reduced aldosterone secretion
Angioedema, rash (esp captopril), diarrhoea, photosensitivity, psoriasis
Elevated hepatic aminotransferase = start of liver damage
Hyponatraemia = aldosterone inhibition –> reduced Na retention
Explain the cough associated with ACE inhibitors
Type of cough = persistent, non-productive cough, mild-tolerable
- Cough is not dose dependent and occurs days-months after treatment has started
How long does the ACE inhibitor cough take to subside?
Improves within 1-4 weeks after stopping medication
How long after commencing treatment of ACE inhibitors could angioedema appear?
First week of treatment (possible months to years later)
Are ACE inhibitors recommended in diabetic patients?
Yes! It is recommended in patients with albuminuria or inc. serum creatinine
ACE inhibitors have a renoprotective effect
They do carry the risk of renal failure with bilateral renal artery stenosis
Why do ACE inhibitors increase the risk of renal failure in patients with Bilateral renal artery stenosis?
Due to the renal stenosis, there is already a reduced GFR/blood entering the glomerulus.
ACE inhibitors will act to further decrease this GFR due to inhibition of ACE, preventing an increase in GFR and ATII formation.
What are the targets of angiotensin? (what are the receptor functions)
AT1 Receptor = contract vascular smooth muscle, secrete aldosterone (adrenal cortex), increase Na+ reabsorption from PCT, increased NA release, stimulation of cell growth in arteries and heart.
AT2 Receptor= influences bradykinin