Block 2 - HTN Med Chem Flashcards
(42 cards)
Describe the RAAS and where its components come from?
Angiotensinogen (Liver) → Renin (Kidney) → Angiotensin I → ACE (Zinc protease, kidney and lung) → Angiotensin II
What are the different controls of angiotensinogen?
GC, thyroid hormones, angiotensin II
What controls renin release?
Aspartyl protease
JG cells sense stretching of arteries and increase in NaCl flux in kidneys → BP increases → Decrease in renin release
Describe how zinc protease converts angiotensin I to II?
R-A system need Leu-His-Phe
ACE cleaves His-Phe stopping at Pro due to its penultimate position
Decapeptide → octapeptide
What are the outcomes of angiotensin II formation?
- Increased PVR (rapid pressor response)
- Regulation of renal function (slow pressor response)
What are the classes of ACEIs?
- Sulfhydryl
- Dicarboxylate
- Phosphate
What falls under the sulfhydryl ACEI?
Captopril
What attributes to ACEIs poor oral bioavailability?
Peptides get metabolized into amino acids therefore IV prevents first pass metabolism
What is the SAR of ACE inhibitors?
- O= for chelation with Zn2+
- O= for H-bonding
- R1 and R2 (hydrophobic pocket) and R3
- COO- for hydrophilic binding
Why is captopril considered the most effective sulfhydryl ACEIs?
-SH brings more chelation with zinc, COO- for ion-ion binding
What are the major ADRs of Captopril?
Capoten has sulfur
1. Smell
2. Metallic taste
3. Skin rashes
4. Loss in taste, drug can bind to taste buds → taste fatigue
What are the metabolites of Capoten?
Captopril metabolizes into disulfide dimer and captopril-cysteine disulfide which are both inactive
In what ways did decarboxylate ACEs differ from Captopil?
- w/o Sulfur, instead was replaced with dicarboxylate
- Although, COO- didn’t chelate zinc as well, manufactures added a transition group that mimicked Ang I
What is the purpose of R1 and R2 side chains on ACEI?
Binding to Lys and His respectively
Why did Enalapril have terrible bioavailability? How was it fixed?
Vaster was too poor, dicarboxy ionized and didn’t absorb well
Transformed into a prodrug to increases is F
Describe the SAR of dicarboxyl ACEI?
R1: CH3 except for Lisinopril
R2: CH2CH3 attached to COO that get cleaved (prodrug)
R3: Lipophilic ring
Ring: contains COOH
How does phosphate ACEI differ from its predecessor?
- Phosphate chelates just as well as sulfhydryl
- Transition state mimics better than decarboxylates
What is the phosphate ACEI? Why is it a good drug?
Fosinopril has a stable phosphate ester, prodrug gives it great bioavailability
What is the most important ADR of ACEI?
Persistant cough due to build up of BK in lungs
Hypotension
Hyperkalemia
What is the ARB site of action?
AT1
What are the actions of AT2?
Anti-AT1: Vasodilation and hypotension
Apoptosis, cell differentiation, tissue repair
What are the actions of AT4?
Release plasminogen activator inhibitor I
Can increase BP by cooperating with ANG II on AT1
How did ARBs development start?
Mimicking ANG II
Saralasin had a ILe to Val substitution, however, since it was a peptide it had poor PO F due to peptide metabolism
What are the important SAR for ARB binding?
- COOH for ion-ion binding
- Hydrophilic rich for H-bonding can be lipophilic some
- Lipophilic group for hydrophobic pocket