Anti Hypertensives II Flashcards
On which receptor does Angiotensin II act?
The AT-I receptor
What is the basis of the hypotensive effects of ACEi?
- Inhibit the vasconstrictive effect of ATII
2. Stimulating action on the Kallikerin-kinin system
How do ACEi affect Aldosterone?
Secretion of Aldosterone is reduced but not seriously impaired
How do ACEi affect renin and Angiotensin-I?
Production of Renin and Angiotensin-I is increased
What happens to the Ang-I in presence of ACEi?
Directed down an alternative pathway resulting in increased production of vasodilator peptides like Ang 1-7 which is believed to be protective
How do ACEi affect renal perfusion?
ACEi increase renal blood flow via vasodilation of the afferent and efferent arterioles
Where does ATII act in the kidney and what are its actions?
In the proximal tubule and it causes the retention of Na+ and H20!
What is PK-C?
A transcription factor for the genes responsible for neo-intima thickening
What is the effect of ACEi on PK-C?
Binding of Ang-II to the AT-I receptor results in theincrease of PK-C which further results in intima thickening this is inhibited by ACEi
How do ACEi affect Baroreceptor mechanisms?
Baroreceptor mechanisms are not affected, postural hypotension is not seen!!!
What condition would predispose a patient to have a na even greater decrease in BP while taking an ACEi?
Subjects with NA+ retention or high Renin
What is the additional benefit of Captopril?
Captopril increases the synthesis of prostaglandins in vascular renal endothelium and delays and even prevents the progression of renal disease in type I diabetics
Which ACEi is renoprotective?
Captopril
Whick of the ACEi are prodrugs?
Enalapril, and Ramipril
When is Enalaprilat mostly used?
IV in hypertensive emergencies
Besides Captopril what is the other renoprotective ACEi?
Lisinopril
Ramipril, what are its advantages?
It has a long half-life so it can be given once a day
What are the contraindication of ACEi?
- Patients ho take potassium or an potassium sparring diuretics, may cause hyperkalemia
- Contraindicated in pregnancy 2nd and 3rd trimesters
- In patients with renal artery stenosis
What are the side effects of the ACE inhibitors
- Dry Cough
- Possible Angioedema which could be fatal
- Hypotension in hypovolemic and or Na+ depleted patients
How to ARB work?
Selectively block AT II type receptors which are responsible for all of the vascular, renal and central effects of AngII
What are the beneficial actions of ARBs?
1.Cause vasodilation and Na+ and water excretion thus reducing TPR, plasma volume, CO, and BP
What is the effect of ARB on ACEi?
No effect on Bradykinin so they don’t produce the cough of ACEi
What is another protective side effect of ARBs?
They do not block the action of AII on AT2 receptors which is thought to be protective
What is the most Potent metabolite of of the PRODRUG LOSARTAN?
EXP 3174
What are the two added actions of Losartan?
- Increases Uric Acid urinary excretion (Uricosuric)
2. Is a Thromboxane A2 receptor competitive antagonist that attenuates platelet aggregation
How does Losartan affect CYP?
Lorsartan is a CYP inhibitor,
What are the differences between Irbesartan, Varlsartan, Telmisartan and Losartan?
Irbesartan, Varlsartan, and Telmisartan do not inhibit CYP enzymes or affect uric acid excretion
What is the ARB used in patients with HTN and GOUT?
Losartan
Which of the ARBs are Prodrugs?
Losartan and Valsartan
Which of the ARBs is not cleared by the Kidney?
Telmisartan
Which ARB has that shotest half life and which has the longest?
Losartan has the shortest and Telmisartan the longest