Block 2 - Dyslipidemia Med Chem Flashcards
Know how cholesterol is degraded?
Know the biosynthesis of TG?
What are the drugs within the bile acid sequestant class?
- Cholestyramine (Qestran, Prevalite)
- Colestipol (Colestid)
- Colesevelem (Welchol)
Describe the MOA of bile acid sequestants?
“Selectively” bind the negatively charged bile acids over other anions
What was Cholestyramine initially developed for?
Pruritus from increased bile acids
Describe the structure of Questran?
Polymer of styrene and cross linked with divinylbenzene
Describe the mechanism and treatment target of bile acid sequestrants?
Why is Questran poorly absorbed and not metabolized very well?
- Cholestryamine has decreased bioavailability in plasma
- Permanent charged amino decreases absorption
- Polymeric and very lipophilic structure
How does Colestipol different from Cholestryamine?
Colestid posses a more ionizable nitrogen → more bile acid binding per unit
Secondary/Tertiary amines ionized at intestinal pH
___ of tertiary amine leads to better binding of Colestid?
Methy iodide quaternization
Describe how Colesevelam fits the SAR of bile acid sequestrates?
- Polymeric
- 0% F
- Act in gut (localized)
- Changed amine
What are the ADRs of BA sequestants? How can it be avoided?
- Constipation: co-admin with dietary fibers or psyllium laxatives
- Worsen hypertriglyceridemia
- Should not be coadministered with other drugs (1 hr before or 4 hr after)
How does BAS induces TG synthesis?
Decreased BA → increased TG for decreased cholesterol → VLDL levels rise → Increase LDL receptors and return VLDL levels to pre-drug levels
A patient with pre-existing hypertriglyceridemia, leads to an increase in triglycerides
What is the MOA of HMGRI?
Inhibition of HMG-CoA reductase → Reducing biosynthesis of cholesterol → Compensatory increase of HMGCoA reductase and LDL receptors → Increased uptake of LDL → Cholesterol lowering
Treatment targets of HLD
How was Mevastatin discovered?
Consisted of Compactin that was a metabolite of Penicillium
Lovastatin (_____) is ___ more potent than Mevastatin
Mevacor; 2x
Describe the transition state of HMGCOa Reductase drugs
Describe HMGRI SAR?
- lactone ring was substituted to bicyclic ring other rings as long as it was lipophilic and contained ethylene bridges
- 7-substituted-3,5-dihydroxyheptanoic acids
Lovastatin Brand
Mevacor
Describe the metabolism of Mevacor?
Lovastatin undergoes lactone hydrolysis → Active from → Metabolized to more hydrophilic metabolites 6-OH or 3-OH
Increasing hydrophilicity doesn’t necessarily mean decreased activity
What HMGRI are prodrugs? Are they activated by esterase?
Lovastatin, Simvastatin
Lactone hydrolysis
How does Simvastatin differ from Lovastatin?
Additional methyl group
How does Pravastatin differ from Zocor and Metacor?
Pravachol has No lactone → Not a prodrug
17% F
Lovastatin/simvastatin = 5%
Pravastatin Brand
Pravachol
Natural
Simvastatin Brand
Zocor
Natural
Fluvastatin Brand
Lescol
Synthetic
Why does Atorvastatin have such long half-life
T1/2: 14-19 hr
Non-naphthalene bicyclic HMGRI
Synthetic
Very bulky and lipophilic
Atorvastatin Brand
Lipitor
How is Lipitor metabolized?
Addition of OH on para or ortho positions
Both equiactive (equal activity)
Why does Rosuvastatin have such a long half life?
T1/2: 19-20
Non-naphthalene bicyclic HMGRI
Synthetic
Bulky, lipophilic, contains a F
Rosuvastatin BRand
Crestor
What is PCSK9?
Protein convertase subtilizing/kexin type 9 that is activated by by proprotein converses to an activated PCSK9
Important for the degradation of LDL-R (normal process for regulation)
What is an examples of PSCK9 Inhibitors?
Alirocumab (Praluent)
Evolocumab (Repatha)
What are some of the characteristics of PSCK9 inhibitors?
- Monoclonal human antibodies
- Longer half-life (14-18 days)
- Dosing Q2W
Alirocumab Brand
Praluent
Evolocumab Brand
Repatha
What is ACL?
ATP-citrate lyase that converts citrate to acetyl-coA
Exampels of ACL inhibitors?
BEmpedoic acid (Nexletol)
What are similarities of citrate and NExletol?
Bempedoic acid is a longer chain → prodrug → binds to CoA (Bempedoyl CoA)
What is the MOA of ACAT inhibitors?
Acyl CoA-cholesterol acyltransferase (ACAT) inhibitors
1. inhibits the synthesis of cholesterol esters
2. Inhibits the esterification of cholesterol in intestinal mucosa
3. Less absorption of cholesterol
Example of ACAT inhibitors?
Ezetimibe (Zetia)
Describe the SAR of ACAT inhibitors?
Pharmacophore for cholesterol absorption inhibitors
How does Zetia undergo metabolism?
Looking at Ezetimibe structure describe its PK properties?
- Crystalline powder
- Long half-life due to out compete cholesterol
Why is ezetimiebe a last-resort drug?
Thicken arterial walls, unknown mechanisms
What are vibrates?
Compounds that lower plasma cholesterol and total lipid levels
Describe fibrate SAR?
- Aromatic ring-O-spacer group-isobutyric acid
- Isobutyric acid (or ester) head group is essential
Class: Phenoxyisobutyric acid
What are fibrite examples?`
- Gemfibrozil (Lopid)
- Fenofibrate (Tricor, Trilipix)
What are some counseling points when using vibrates?
- Indicated for hypertriglyceridemia and familial combined HLD
- Co-administered with other classes
- Should be take with food to increase absorption
What are example of lipolysis inhibitors?
Nicotinic Acid (Niacin)
What is nicotinic acid?
Derivative of nicotine that reduces cholesterol levels in humans and lowers serum triglycerides
Describe the Niacin MOA?
How does Niacin have such a short half-life and fast onset?
Very small and easily identified by metabolic enzymes
ADRs of Niacin?
- Cutaneous VD → flushing/pruritus (Niacin flush)
- Requires titration to prevent ADRs
Is niacin ER good?
- Concurent use with statins → less carotid thickening
- Increased risk for stroke
- Still an ongoing debate
What is ANGPTL3?
- Enzyme that blocks lipoprotein lipase (LPL) and endothelial lipase (EL) → LPL/EL converts VLDL to VLDL remnants (IDL) and IDL to LDL
What happens if you inhibit ANGPTL3?
Production of more VLDL remnants (IDL) which is cleared by HoFH
Shifts the concentration of IDL to lower causing circulating LDL to re-equalibrate to IDL thus less LDL
What are examples of ANGPTL3 inhibitors?
Evinacumab (Evkeeza)
Describe the overall effect of HMG-CoA reductase inhibitor?
Best for LDL control
Describe the overall effect of Fibrates?
Describe the overall effect of Niacin?
Describe the overall effect of Bile acid sequestrants?
Describe the overall effect of cholesterol absorption inhibitors?
Describe the overall effect of PCSK9?
Strong decrease in LDL
Increase in HDL
Describe the overall effect of ANGPRL?
Decrease in TG