3.1.2 ACEis and ARBs Flashcards
What are the 4 types of drugs used in treatment of hypertension?
ACEi
ARBs
CCBs
Diuretics
Where is ACE found?
Luminal surface of capillary endothelial cells
Mainly in lungs
What does ACE do?
Catalyses conversion of angiotensin I to potent vasoconstrictor angiotensin II
Angiotensin-II can be produced from angiotensin-I independently of ACE via chymases
What receptors does angiotensin II bind to?
AT 1 and 2
AT1 is the main one
What does angiotensin II binding at AT1 cause?
Vasoconstriction
Stimulation of aldosterone, acts on distal renal tubule, cardiac and vascular muscle cell growth
ADH release from posterior pituitary
What do ACEi do?
Stops angiotensin-I conversion to angiotensin-II by inhibiting tissue ACE
What does reduced angiotensin-II due to ACEi cause?
Vasodilation, decreased peripheral resistance and afterload
Reduction in aldosterone release
Reduced ADH release
Reduced cell growth and proliferation
Why do patients get a dry cough when they take ACEi?
Bradykinin is also a substrate for ACE, which means that ACE usually converts bradykinin
Use of ACEi therefore increases the potency of bradykinin, vasodilatation via NOS/NO and Prostaglandins
10-15% of patients
What are the adverse effects of ACEi?
Hypotension, more dangerous in elderly, postural hypotension, fall risk
Dry cough, 10-15% of time
Hyperkalaemia, lower aldosterone
Cause/worsen renal failure, especially renal artery stenosis where constriction of EA needed
Angioedema, more common in afro-carribean
When should ACEi not be used?
Renal artery stenosis
AKD
Pregnancy
CKD
Idiopathic angioedema
What can ACEi interact with?
Drugs increasing K+
NSAIDs
Other antihypertensives
What are two examples of ACEi?
Lisinopril
Ramipril
-pril suffix
What do ARBs block?
AT1 receptors
When are ARBs less effective?
If patients have low levels of renin, as this pathway is being blocked so if there isn’t much of an effect on bp from renin, blocking this pathway won’t do much
Dry cough and angioedema less likely than with ACEi
What are some adverse effects of ARBs?
Hypotension
Hyperkalaemia (low aldosterone)
Cause/worsen renal failure
