ACE inhibitors, Angiotensin Receptors Inhibitors And Diuretics Flashcards
What is the vascular endothelium and what are its functions?
A single layer of cells on the inner surface of blood vessels.
Barrier, clotting, angiogenesis, inflammation, vasoconstriction/vasodilation
What potent mediators does endothelium contain?
Vasodilators and vasoconstrictors
What does the renin-angiotensin-aldosterone system (RAAS) regulate?
Blood pressure, blood volume and electrolyte balance
Under what three circumstances would renin be released?
- Reduced sodium delivery to distal convoluted tubule
- Reduced perfusion pressure in the kidney
- Sympathetic stimulation
What hormones are involved in the RAAS?
- Atrial natriuretic Peptide (ANP)
- Vasopressin/antidiuretic Hormone (ADH)
- Aldosterone
What protease Enzymes are involved in the RAAS?
Wouldn’t you like to know cowboy 🤠
What is Angiotensin 2?
An active octapeptide that is a potent vasoconstrictor which increases blood pressure
What does Renin and ACE convert?
Renin - Angiotensinogen to Angiotensin 1
ACE - Angiotensin 1 to Angiotensin 2
Angiotensin 2 activates AT1 receptors which cause what?
- Contraction of vascular smooth muscle
- Secretion of aldosterone
- Increased reabsorption of sodium
- norepinephrine release
- Stimulation of cell growth in arteries and heart
What are some examples of ACE inhibitors?
Ramipril, perindopril, captopril, lisinopril
Where is ACE mainly expressed and what are ACE inhibitors mechanism of action?
In the lungs.
- Binds to the zinc atom in the active site of ACE preventing conversion of Angiotensin 1 to Angiotensin 2.
- Reduction of circulating Angiotensin 2 lowers blood pressure
What drug interactions are there with ACE inhibitors?
Diuretics/CCBs -> effect increased (can be used in resistant hypertension)
Potassium sparing diuretics -> hyperkalaemia
Lithium -> Lithium toxicity
NSAIDSs -> impedes antihypertensive effects
What are the adverse effects of ACE inhibitors?
- Dry cough (buildup of bradykinin usually cleaved by ACE) - major compliance issue
- Can cause foetal injury and death - MUST NOT BE USED IN PREGNANCY
What are examples of angiotensin receptor blockers (ARBs), what is their mechanism of action and what is their advantage over ACE inhibitors?
Candesartan, Irbesartan, losartan.
Selectively block Antgiotensin AT1 receptors, reducing Angiotensin 2 mediated effects.
Do not cause dry cough.
What is the main contraindication of ARBs?
Pregnancy