Dyslipidemia Drugs Flashcards
A 56- year old retired school teacher with treated blood
pressure of 125/82 mmHg comes in for a semi annual
exam.Blood chemistry is showed LDL is 230 and HDL
is 54. You placed him on a drug and asked him to
return after one month. Usually, in managing patients
with dyslipidemia, we advise follow up after a month to
assess the response to treatment as well as the
adverse effect. On his return, his LDL is reduced to 189
but complains of cramping pain in the gastrocnemius
on both legs
The drug that will most likely have this adverse effect is which drug? a. Ezetimibe b. Rosuvastatin c. Hydrochlorothiazide d. Niacin e. Gemfibrozi
LDL is elevated. The ideal level of LDL should be <100.
So which among these drugs used in managing
dyslipidemia may cause myopathy or myositis?
It is the statins as well as Gemfibrozil.
But for this case, the most common drug that is being
used is the statins because they are the first line drugs
in managing dyslipidemia so the answer for this case
is Rosuvastatin
LIPOPROTEIN
Lipoproteins are macromolecular assemblies that contain
lipids and proteins
LIPID (Core)
- Contains Cholesteryl ester, Triglycerides
and Fatty Acids - Water insoluble
- Surrounded by unesterified cholesterol,
phospholipids, and apolipoproteins
PROTEIN (outer surface)
Contains Apolipoproteins namely: § Apo A (seen in HDL) § Apo B (Apo B-48 in Chylomicrons, Apo B-100 in VLDL, LDL, IDL) - They have polar surface and are water soluble
Density and Size are inversely related
As you increase the amount of lipid, it
becomes less dense than water.
- Chylomicrons: more lipid, least dense
• The higher amount of lipid, the larger the
structure. The lower amount of lipid, the smaller
the structure
HDL
most dense, smallest
Chylomicrons:
least dense, largest.
APO LIPOPROTEINS
Responsible for the structural integrity
- Functions as a ligand and bind to different
receptors
- Activates enzymes important in lipoprotein
metabolism
Any lipoprotein that contains Apo B-48 and Apo B-100
can cause
Atherosclerosis
Clinical Sequela: Atherosclerosis and Acute pancreatitis
Main goal of management: lower LDL
CIGARETTE SMOKING
Can increase the risk of developing Atherosclerosis - Effects of cigarette smoking: (DICIS) • Decrease in HDL • Impairment of cholesterol retrieval • Cytotoxic effects on the endothelium • Increased oxidation of lipoproteins • Stimulation of thrombogenesis
CHYLOMICRONS
- Largest lipoprotein
- Contains Apo B-48
- Synthesized from the dietary triglyceride and
cholesterol that comes from the diet.
Chylomicrons are formed in the intestine and carry
triglycerides of dietary origin, unesterified cholesterol,
and cholesteryl esters
Pathway for Cholesterol Transport
- Ingestion of dietary fat
- The cholesterol and the triglyceride present in the diet would be esterified by Type II Acyl Coenzyme Cholesterol Transferase
Esterification: elongation and addition of fatty acid to TAG and Cholesterol.
The esterification is with the effect of Microsomal Triglyceride Transfer Protein (MTP) - Cholesteryl Ester + long chain FA with TAG + apo B48 absorbed in the intestine via Niemann Pick C1L1 = CHYLOMICRON
- Once absorbed, the chylomicron enters the thoracic lymph where in it will be used by the peripheral tissue
before it goes to the liver - Chylomicron will become chylomicron remnants when it is acted upon Lipoprotein Lipase (remove the TAG within the chylomicron) LPL needs a cofactor ApoC2 to be activated
- Chylomicron remnants (less TAG, more cholesterol) would then be endocytosed in the liver (apoE mediated)
- It will then be acted upon by Hepatic lipase
- Degraded
Exogenous pathway
transport dietary lipids to the
periphery and the liver
Endogenous pathway
transports hepatic lipid from the
liver to the peripher
• Chylomicrons are converted to chylomicron
remnants by the hydrolysis of their triglycerides
by LPL.
“Remnant receptors”
nclude the LDL receptorrelated protein (LRP), LDL receptors, and other
receptors.
• Free Fatty acid (FFA) released by LPL is used by
muscle tissue or taken up and stored by adipose
tissue.
The TAG is removed from the Chylomicron by
LPL,
the FA will be stored in the adipose tissue
VLDL will then be hydrolyzed by LPL releasing free FA
producing
IDL
Intermediate Density Lipoprotein (IDL
will be
endocytosed to the liver which is ApoE mediated.
- Further hydrolysis of IDL by LPL and Hepatic Lipase
will release more TAG would produce LDL
Low Density Lipoptotein
would then be endocytosed to the liver which is ApoB mediated - LDL binds to the LDL receptor - Liver would have more cholesterol. - Increased Cholesterol level à LDL receptor down regulated
Decreased Cholesterol level
LDL receptor up
regulated
Chylomicron remnants
can indirectly increase
LDL level but do not serve as a precursor for LDL
synthesis.
LOW DENSITY LIPOPROTEIN
LDL are catabolized chiefly in hepatocytes and other cells
after receptor-mediated endocytosis.
- Clearance is mediated by LDL receptor
- Apo B100 is the ligand that binds LDL to its receptors (that is why it is called “BAD
CHOLESTEROL)
- Become atherogenic when they are modified by oxidation à FOAM CELL formation
- Increased LDL receptor à decreased LDL level
HIGH DENSITY LIPOPROTEIN
APO A1 is the major HDL apoprotein
1. The membrane transporter ABCA I facilitates the transfer of free cholesterol from cells to HDL
- As Cholesteryl ester of HDL increases à Cholesteryl ester begin to be exchanged for TAG
derived from any TAG containing Lipoprotein mediated by Cholesteryl Ester Transfer Protein (CETP) - HDL cholesterol selectively taken up by the liver via SR-BI (scavenger receptor class B1
Good cholesterol results from participation of HDL in Reverse Cholesterol Transport =
excess cholesterol is acquired from cells and transferred to the liver for excretion