usmle4life wrote:
hey I have a question about Losartan...it is an angiotensin 2 receptor blocker..but does it increase angiotensin 1??? plzzz let me know..i was confused about the MOA of this drug..I would really appreciate!
all you need to know about losartan is that it is an Angiotenisin receptor blocker for AII. ACE normally promotes the breakdown of bradykinin and converts AI into AII. patients that cannot tolerate an ACE-inhibitor usually do so b/c of an increase in bradykinin (ACE is inhibited so bradykinin is not broken down.) By putting them on an ARB (losartan), you allow ACE to cleave bradykinin and break it down, but prevent the effects of AII, which is in effect the same thing an ace inhibitor is doing.
Note that AII is still formed from AI with losartan, but AII is not allowed to bind to its receptor b/c losartan is antagonizing the receptor.
so to answer your question, with losartan, AII is increased but is not able to act. AI is increased to form more AII, but this honestly has nothing to do at all with the action of the drug or its actions.
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| tolito
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Good explanation. some questions ask abot the levels of AI,II and renin following use of ACEI and ARB.
with ACEI renin levels go up due to lack of negative feedback from AII whcih is not being produced. with ARB, AI and AII levels go and renin goes down.
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| pocas
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 good explanation
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