A lot of people are dying these days
because of cardiovascular diseases like
Myocardial infarction which is mostly due
to obesity and various other associated
factors. Increased blood cholesterol is
obviously a major risk factor for such
diseases. So decreasing the blood
cholesterol is a very important measure
to control such diseases. In this video
I'll be talking about the drugs which
can reduce blood cholesterol and
effectively decrease cardiovascular
diseases. What's going on you guys? You're
watching Med Vids Made Simple. If you are
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nearby to watch all my new upcoming
videos as soon as I upload them. Before
talking about the drugs let me tell you
about the lipoproteins which are
involved in cholesterol and triglyceride
transport in the body. The major
lipoproteins are chylomicrons, very
low-density lipoprotein also called as
VLDL, intermediate density lipoprotein
called IDL, low density lipoprotein
called LDL and high density lipoprotein
called HDL. So having a basic idea let's
now jump right into the drugs used. The
drugs which are used to lower the blood
cholesterol levels are statins, resins
fibrates,
nicotinic acid which is also called as
niacin and sterol absorption inhibitors
which includes ezetimibe. First let's
talk about statins now I'm pretty sure
someone in your family or relatives would
be taking a statin for sure because it's
very commonly used. Now how do they work?
Have you ever heard of the enzyme called
HMG CoA reductase? It is a very
important enzyme which is involved in
control synthesis in the body. The
statins effectively inhibit the HMG
Co-A reductase enzyme, as a compensatory
mechanism in the liver there will be
increased breakdown of LDL cholesterol
so increased breakdown of LDL
cholesterol will lead to decrease in the
LDL level in the body.
examples of statins includes
atorvastatin, simvastatin and
rosuvastatin
the most commonly used statin is atorvastatin. It is also very potent, the
dosage of atorvastatin is about 10
to 40 milligram per day and it is most
commonly given in nighttime because HMG
Co-A reductase enzyme is very active in
the night time. remember that these drugs
are metabolized by CYP3A4 system of
enzymes in the liver, so the drugs which
have effects on CYP3A4 will also have
effects on statin metabolism. now let's
talk about the side effects of statins
these are usually mild
headache and GI distress symptoms. the
most severe adverse effect of statins is
myopathy and this can get even worser
when some other
hyperlipidemia drugs are given along
with it. Now let's talk about resins.
resins are basically bile acid
sequestrants. what they actually do is
they bind to bile acids in the intestine
and prevent their enterohepatic
circulation, when they prevent the
enterohepatic circulation of the bile acids,
the bile acids are increasingly excreted
in the feces so what happens is there
will be low bile acids available for entero
hepatic circulation. To overcome that,
more of the cholesterol present the body
is used up for production of bile acids
by the liver so this will decrease the
blood cholesterol levels in the body
there will also be decreased LDL levels in the
body because of compensatory mechanism
these drugs are very effective but still
they are associated with very
discomforting side effects such as
flatulence, dyspepsia and associated
symptoms, so the patients
mostly are not compliant
with these drugs. These drugs are not
commonly preferred by
the doctors also because of low
compliance of the patients. Examples of
resins includes cholestyramine
and colestipol. Now let's talk about
fibrates which are very important drugs.
Fibrates are lipoprotein lipase
activators. Do you know where this enzyme is
present and what it does? It is present
in the endothelium of capillaries of
adipose tissue, muscles and heart. The
mechanism of action is by activating
PPAR alpha. PPAR alpha stands for
peroxisome proliferator activator receptor alpha.
It is a gene transcription regulating
factor which activates lipoprotein
lipase synthesis. Once the PPAR alpha is
activated this will lead to activation
of lipoprotein lipase. The lipoprotein
lipase will cause degradation of very
low-density lipoprotein and this will
lead to decreased triglycerides level in
the blood because VLDL is the major
carrier of triglycerides. Since VLDL is
the thing which is going to break down
to IDL and LDL, when VLDL is
decreased, IDL and LDL are also
decreased. Examples of fibrates includes
gemfibrozil, bezafibrate and
fenofibrate. So the side effects of
the fibrates includes GI disturbances
and associated side effects. These drugs
are found to increase the risk of
myopathy of statins when they're given
along with it. These drugs are found to
be very effective in preventing atherosclerotic events by various clinical
trials. Now let's talk about nicotinic
acid which is also called as niacin
so you all must be knowing it is vitamin
b3. It is found to be the most effective
drug in reducing plasma triglyceride
levels and it is also found to be very
effective in increasing the good
cholesterol which is HDL cholesterol
It also decreases lipoprotein A which is
found to be the most atherosclerotic
agent. It can also decrease very
low-density lipoprotein and by doing so
they can also decrease IDL and LDL. The
side effects of these drugs include
flushing because it's a peripheral
cutaneous vasodilator and they can cause
dyspepsia, vomiting, diarrhea and liver
damage. These drugs are found to increase
the blood sugar levels so they should
not be used in diabetic patients but
these drugs when given on a long-term
basis can prevent pancreatitis events in
hyperlipidemic patients. Finally let's
talk about sterol absorption inhibitor
which includes ezetimibe. Ezetimibe is
a sterol absorption inhibitor. It
inhibits NPC1L1 which is a
cholesterol transport protein present in
the bowel wall, so this decreases the
cholesterol absorption from the gut. As
a compensatory mechanism as usual,
there will be increased LDL breakdown in
the liver, that will lead to decrease in LDL also. This drug is often used with
low dose statin for better effects. The
side effects of this drug includes
hepatic dysfunction and myositis. For
completion sake, let's talk about CETP
inhibitors too. Cholesteryl ester
transfer proteins is what is actually
CETP and these are mainly secreted from
liver. The CETP is actually involved in
transfer of cholesterol from HDL to LDL,
so there will be decrease in HDL and
increase in the LDL. So what we are
trying to do is, we are giving drugs
such as torcetrapib and anacetrapib
which can inhibit the cholesteryl ester
transfer proteins and thereby preventing
transfer of cholesterol from HDL to LDL
This will lead to increased HDL and
decreased LDL. But these drugs were found
to be not so effective
by clinical trials, so they're not commonly used.
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