Glossary of drugs and medical terms
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
A
active agentThe active agent of a drug drug is the chemical substance that causes the effect, and it often differs from the drug's brand name. For example the name of a popular cholesterol-lowering drug is Lipitor® manufactured by Pfizer, but the name of the active agent in Lipitor® is atorvastatin. Generic drugs which are generally cheaper than the original drugs are often named after the active agent such as "Simvastatin Tablets" by IVAX Pharmaceuticals (original drug: Zocor® by Merck & Co.).
aneurysm
Origin: Greek "aneurysma" = widening.
angina pectoris
Chest pain caused by insufficient supply of oxygen to the heart muscle. The underlaying cause is often a narrowing of the arteries by
atherosclerosis that causes acute problems during times of physical or psychological stress when more oxygen is required.
apolipoprotein
Proteins that form the outer shell of lipoproteins are called apolipoproteins or apo for short. Apolipoproteins contribute by making lipoproteins water-soluble
so that cholesterol and triglycerides can be transported in the arteries. Each
lipoprotein type has a specific subset of apoproteins such as HDL particles that carry
mainly apolipoprotein A and LDL which carries predominantly apolipoprotein B100. Cells
can discriminate between each type of lipoprotein particle by reading this "bar code"
of lipoproteins with special receptors.
arteries
Arteries are the blood vessels that deliver blood from the heart to the
body, opposed to the veins that return blood from the body to the heart. Blood
pressure is always measured for the arteries, where approximately 120 mmHg ("systolic" - when the heart beats) over 80 mmHg ("diastolic" - in-between two heart
beats) is considered normal. The abbreviation mmHg stands for "millimeter of mercury" and dates back to a time when mercury-filled tubes were used for pressure measurements.
arteriosclerosis
Origin: Greek "hardening of the arteries" The term arteriosclerosis describes
the general phenomenon of arteries becoming less flexible and elastic, by a
hardening and thickening of the artery walls, regardless of the underlying disease.
In contract, atherosclerosis is a specific type of arteriosclerosis involving
the buildup of cholesterol-containing plaque inside the artery walls. However, these terms are often
used interchangeably.
atheromatous plaque
Please see atherosclerosis
atherosclerosis
Origin: Greek "hardening due to the formation of atheromatous plaque"
- When arteries leading to limbs are affected, circulation problems may develop in arms and legs called peripheral arterial disease
- When arteries to the heart are affected, coronary artery disease, chest pain (angina) or a heart attack can result
- When arteries supplying blood to the brain are affected, a transient ischemic attack or stroke could follow
- Atherosclerosis can also lead to a bulge in the wall of your artery called an aneurysm
atorvastatin
Atorvastatin belongs to the the drug class of statins, effective against
high cholesterol. With 2005 sales of US $12.2 billion under the brand name Lipitor®
(manufactured by Pfizer), it is the highest selling drug worldwide.
B
bad cholesterol
Please see LDL
bypass surgery
During bypass surgery, arteries or veins from elsewhere in the patient's
body are transplanted to the heart to bypass atherosclerotic coronary arteries
to improve the blood supply to the heart muscle.
C
cardiovascular
Regarding the heart "cardio" and blood vessels "vascular"
CEPT
inhibitors
CETPs or cholesteryl ester transfer proteins are liver enzymes
that transfer cholesterol from HDL to LDL particles, turning "good" cholesterol into "bad"
cholesterol. The primary effect of inhibiting CEPTs is a significantly increased
serum HDL cholesterol level, with the lowering of bad LDL cholesterol a positive
side effect.
This approach has been criticized since Pfizer's torcetrapib failed to lower heart problems in a recent clinical trial. As an unforeseen side effect, it actually raised blood pressure, thereby increasing heart problems and the overall risk of death.
cholesterol
Cholesterol is a fat-like substance that is vital to the human body. It
is a component of every body cell, helping to maintain the stability and fluidity
of cell membranes. Cholesterol is also used in the liver to produce cholic acid,
a major constituent of the bile fluid necessary for the digestion of fat. Most
of the body's cholesterol is made in the liver,
but some is absorbed by food. Excessive blood cholesterol can lead to atherosclerosis.
Chylomicrons belong to the lipoprotein particles or tiny spheres that carry fat molecules throughout the blood stream. Chylomicrons are responsible for transporting fat and cholesterol absorbed by the gut through the bloodstream to various body tissues, mainly the liver.
coronary artery disease
Disorder of the coronary arteries that supply the heart muscle,
usually narrowing or even complete blockage caused by atherosclerosis. This
can lead to angina and eventually a heart attack. During bypass surgery, vessels
that bypass the blocked arteries are implanted to improve blood flow to the heart.
Crestor®
The drug Crestor® contains the active ingredient rosuvastatin which can lower
LDL cholesterol by approximately 40% when taken in a standard dose of 5-10 mg per
day, and by up to 50% or more at higer doses. Rosuvastatin and atorvastatin
(Lipitor®) are currently the most potent LDL cholesterol lowering drugs available. Crestor®
is marketed by AstraZeneca under a license from Shionogi, Japan.
D
diastole
Please see arteries
E
entero-hepatic cycle
A shuttling of cholesterol between the gut "entero" and liver "hepatic."
Cholesterol is secreted with the bile fluid coming from the bile bladder in
the liver and combines with cholesterol from food in the small intestine.
The combined cholesterol is then partially secreted in stools, and partially
reabsorbed only to end up back in the liver. The entero-hepatic cycle is believed to be a way the body eliminates excess cholesterol, although this mechanism
is clearly not fine tuned, at least in individuals with high cholesterol.
ezetimibe
Ezetimibe is the active agent of the drug Zetia® (marketed by Merck
and Schering-Plough). It is not a statin, and works with a mechanism entirely
different to those of statins by blocking the uptake of cholesterol in the gut.
Ezetimibe may be taken by patients who can't tolerate statins.
F
fibrate
Fibrates such as clofibrate are cholesterol and triglycerid-lowering drugs.
G
gangrene
Death of tissue, usually due to insufficient oxygen supply. Typically, the narrowing
or even complete blockage of the arteries of the legs with with pain walking or
even death of foot or leg tissue is called gangrene, which is roughly comparable
to "smoker's leg"
good cholesterol
Please see HDL
H
HDL
HDL particles (high density lipoproteins) are a subclass of the lipoprotein
particles or tiny spheres that carry fat molecules throughout the blood stream. HDL
particles are able to collect cholesterol from body cells for reprocessing
or elimination through the bile fluid) in the liver. By doing so, they provide
a method to eliminate excess cholesterol that may otherwise accumulate in the body.
The important thing is that they can also absorb cholesterol from artery
walls which slows the buildup of plaque. These mechanisms counteract the harmful
effects of high LDL cholesterol and may slow the progression of atherosclerosis.
That's why HDL is also called "good" cholesterol. HDL cholesterol
present in HDL particles is actually an indicator of how many
vessel-cleaning HDL particles are present. HDL cholesterol is the
only form of cholesterol you actually want to increase.
HDL cholesterol
All the cholesterol present in HDL particles is called HDL cholesterol.
Because HDL cholesterol is comparatively easy to measure, it serves as a proxy for
the number of HDL particles which are difficult to count. Although HDL cholesterol
contributes to total cholesterol, you want to increase the amount of
this "good" cholesterol; having many HDL particles in your blood can
delay the buildup of plaque in your arteries.
heart attack
Sudden blockage of coronary arteries such as blood clots forming in atherosclerotic
arteries can result in a heart attack, also known as a myocardial infarction. During
a heart attack, a part of the heart muscle is no longer supplied with oxygen
and nutrients. This part of the heart muscle may die if the blockage is not
dissolved rapidly by medication and/or natural clot-dissolving processes in
the body. Symptoms include a crushing chest pain that may radiate to the jaw
or left arm, nausea, sweating and shortness of breath. Fainting is not very
common.
HMG-CoA reductase
HMG-CoA reductase is a key enzyme in the synthesis of cholesterol
in the liver.
HMG-CoA reductase inhibitor
Drugs that impede HMG-CoA reductase, the key enzyme responsible for
the body's synthesis of cholesterol in the liver. The body produces less cholesterol,
which decreases the blood levels of cholesterol. Statins, the most important
anti-cholesterol drugs currently available, are HMG-CoA reductase inhibitors.
hypercholesterolaemia
Origin: Greek "Haima" = blood. High blood cholesterol or literally too much (hyper) cholesterol in the blood.
hyperlipoproteinaemia
Greek "Haima" = blood. High blood lipids or literally too much (hyper) lipids in the blood. A somewhat imprecise term to indicate that any one or more
of the blood lipids is too high.
hypertriglyceridaemia
Greek "Haima" = blood. High blood triglycerides or literally too much (hyper) triglycerides in the
blood.
I
J
K
L
LDL
LDL particles (low density lipoproteins) are a subclass of the lipoprotein
particles or tiny spheres that carry fat molecules throughout the blood stream. LDL particles,
however, only carry cholesterol to the tissues throughout the body. The entire LDL particles
are absorbed by body cells, which then use the cholesterol as building blocks
for their cell membranes. Leftover LDL may return to the liver, where it is
absorbed for storage and reprocessing. If too much LDL cholesterol is present
in the blood, it tends to be deposited in the artery walls as soft, wax-like
plaque. This is the first step towards atherosclerosis or hardening of the
artery walls which can ultimately lead to heart disease.
LDL cholesterol
All the cholesterol present in LDL particles is called LDL cholesterol.
LDL cholesterol is called "bad" cholesterol, and at high blood levels can be
deposited in artery walls, leading to atherosclerosis.
Lescol®
The drug Lescol® contains the active ingredient fluvastain and is marketed by Novartis. It can lower LDL cholesterol by approximately 30% when taken in a standard dose of 40mg per day.
lipid
Biological substances that are soluble in fat, but not water
are called lipids. Among the lipids are triglycerides such as oil and fat, cholesterol,
fatty acids and phospholipids (lecithin).
Lipitor®
Lipitor® manufactured by Pfizer is a potent LDL cholesterol lowering drug, containing
the active ingredient atorvastatin. It can lower LDL cholesterol by approximately 40%
when taken in a standard dose of 10-20mg per day. Lipitor® is the world's
best-selling drug, with 2006 revenues of nearly $13 billion, out of a worldwide
total of $35 billion for statin drugs.
lipoprotein
Being a fat-like substance, cholesterol is not water soluble. It can't flow
freely through the blood, but quickly forms fatty droplets
like grease drops in soup. The body's solution is to transport cholesterol,
fat and oil (triglycerides) in specialized vehicles called lipoproteins.
Lipoproteins, "lipoprotein complexes" or "lipoprotein particles" are tiny
spheres that carry fat molecules throughout the blood stream. They consist of a
water-soluble outer protein layer resting on a membrane of phospholipids which is another
fat-like substance and an inner storage space holding cholesterol
or cholesterol and triglycerides. Examples of lipoproteins include HDL or LDL particles
and chylomicrons.
lipoprotein a, Lp(a)
Subclass of LDL particles containing the apolipoprotein 'a'. Apolipoprotein
a counteracts the body's natural ability to dissolve smaller blood clots and
increases the buildup op plaque in the arteries. High concentrations of Lp(a)
in the blood are considered to be especially harmful for cardiovascular
health.
Lopid®
The drug Lopid® contains the active ingredient gemfibrocil which belongs to
the fibric acid drugs known as "fibrates." These drugs are used to lower serum triglycerides
by as much as 60%, and may raise HDL cholesterol by as much as 20%. When combining fibrates
with a statin drug, gemfibrocil seems to be the best choice, given that adverse drug
interactions appear to be comparably low. Lopid® is marketed by Pfizer.
lovastatin
Lovastatin was the first statin approved by the FDA in 1987 under the brand
name Mevacor® (manufactured by Merck).
M
Mevacor®
The drug Mevacor® contains the active ingredient lovastatin which
can lower LDL cholesterol by 30-40% when taken in standard
doses of 20-40mg per day. Introduced in 1987, Lovastatin is the oldest statin
on the market which means that its safety
has been extensively studied. Mevacor® is marketed by Merck, which currenly
plans to obtain approval for a prescription-free version of 20mg lovastatin
per day.
micelles
Micelles are tiny spheres appearing in the gut after a meal. They are filled
with cholesterol and fat, and are absorbed by cells lining the gut. Without
micelles, cholesterol and fat could not be absorbed efficiently.
myocardial infarction
Please see heart attack
N
niacin
Substances that have vitamin B3 activity are collectively known
as niacin. In fact, there are two substances that have Vitamin B3 activity:
nicotinic acid and nicotinamide. 14-18mg of nicotinic acid per day
is sufficient to satisfy the vitamin needs. However, when increasing the dose to 500-2000mg a day or up to 100-fold, it has drug properties and can raise HDL cholesterol
by 15-30%, and may reduce serum triglycerides by 40-50%. A common side effect
is facial flushing or reddening of the face and neck, sometimes accompanied by a
burning or itching sensation. Nicotinamide, the other Vitamin B3, does not influence
these lipids. Since niacin is the collective term describing both nicotinic
acid and nicotinamide, it is not correct to state that niacin raises HDL or lowers
triglycerides.
Niaspan®
Niaspan® is an extended-release formula of nicotinic acid manufactured
by Abbot Laboratories. The purpose of extending the release of the drug over
a longer time period is mainly to lower flushing, the most common side effect
of nicotinic acid.
nicotinic acid
Nicotinic acid (Vitamin B3 - also see "niacin") can raise HDL cholesterol
and lower serum triglyceride levels when taken in large amounts (500-2000mg a day). Nicotinic acid is the active agent in Niaspan®.
O
P
peripheral artery disease
Peripheral artery occlusive disease (PAOD) are ones in which
the large peripheral arteries that are distant from the body center (most
commonly the legs) are blocked, mainly due to atherosclerosis. Symptoms of
severe PAD include constant leg pain, foot or toe wounds that heal very slowly and
gangrene.
phytosterol
Phytosterol is a plant-derived mixture of lipids that is chemically
similar to cholesterol. It competes with cholesterol for the limited uptake
capacity of cholesterol in the gut. Consequently, less cholesterol is absorbed.
Phytosterols (plant sterols) can be used to lower blood cholesterol
levels; a 2g daily dose may lower LDL cholesterol by 10-15%. One phytosterol called
sitosterol was introduced by Eli Lilly in the 1950s under the brand name
Cytellin. It had a very high safety record. However, with the development
of statins, phytosterols became obsolete as prescription drugs. They can currently be found in dietary supplements or fortified products such as spreads and yogurts
(eg in Take Control®/Promise® products by Lipton/Unilever).
Pravachol®
entry pending
Q
R
risk factors
Risk factors are habits or traits that increase the likelihood of certain
diseases such as heart disease. Some important risk factors for heart disease
include: high cholesterol, high blood pressure, smoking, physical inactivity and
being overweight.
S
Simcor®
Simcor® is a new fixed-dose drug combination consisting of Niaspan®
to raise HDL cholesterol and simvastatin to lower LDL cholesterol. It is
currently develoed by Abbot Laboratories and may be introduced into the market
by 2008.
simvastatin
One of the earlier statins which are powerful drugs against high cholesterol.
Simvastatin is the statin used in the drug Zocor® (manufactured by Merck).
sitosterol
Sitosterol (beta-sitosterol) is the predomminant phytosterol in plants.
statin
Statins are drugs that interfere with the biosynthesis of cholesterol
in the liver, leading to lower blood levels of total cholesterol and LDL cholesterol.
The "good" cholesterol HDL-C is usually not affected. Statins are quite powerful
for reducing cholesterol levels -- a 30-50% reduction may be achieved with normal
doses. Statins are also called HMG-CoA reductase inhibitors because they suppress
the liver enzyme central to cholesterol synthesis, 3-hydroxy-3-methyl-glutaryl-CoA
reductase (HMG-CoA reductase). Examples of statins include atorvastatin (in the
drug Lipitor® manufactured by Pfizer) and simvastatin (in the drug Zocor® manufactured by
Merck).
stroke
Brain damage caused by an interruption of the blood and oxygen supply
due to blockages by blood clots or the bursting of blood vessels. The severity
of damage is dependent on the region of brain affected, the extent of the
oxygen deficient area, and the time until the blood supply is re-established
(transient ischemic attack).
systole
Please see arteries
T
thrombosis
Forming of a thrombus or coagulation of blood in blood vessels, frequently
causing obstructions at the site of formation and further down the
bloodstream. This can lead to a heart attack or stroke.
total cholesterol
The overall concentration of cholesterol measured in the blood.
Nowadays, considered only to be a crude estimate of a person's heart disease
risk. The allocation of total cholesterol to the different lipoproteins
such as LDL and HDL are also measured, becuase they are more accurate in determining
if medical intervention is required.
transient ischemic attack
A stroke with only transient loss of brain function due to insufficient
blood flow in a region of the brain. Individuals normally experience a complete recovery within 24 hours.
triglycerides
Fat and oil are considered triglycerides, and are chemically comprised of
glycerin and three "tri" fatty acids.
U
V
veins
Veins are the blood vessels that return blood from the body to
the heart, as opposed to arteries that deliver blood from the heart to the body).
Blood pressure is always measured for the arteries, and is much lower (below
10 mmHg) in the veins.
Vytorin®
The drug Vytorin® contains a combination of the active ingredients simvastatin
and ezetimibe. As a mono-drug, simvastatin can lower LDL cholesterol by approximately
30-40% when taken in standard doses of 20-40mg per day.
Ezetimibe as a mono-drug can lower LDL cholesterol by approximately 20%. Because the combination
can lower cholesterol by approximately 50% or higher, Vytorin® is usually taken
by patients at high coronary risk. Vytorin® is marketed by Merck and Schering-Plough
under the tradename "Inegy."
VLDL
VLDL particles (very low density lipoproteins) are lipoproteins that carry
cholesterol and fat throughout the bloodstream. These particles are released from
the liver into the bloodstream. They are similar to chylomicrons which originate
from the gut because they both carry cholesterol and triglycerides which are gradually
released in the bloodstream to be absorbed by body cells along the way. In the
process of losing triglycerides, the VLDLs grow smaller and turn into
IDLs (intermediate-density lipoproteins) and finally into LDLs which have
lost all their triglycerides.
W
X
Y
Z
Zetia®
The drug Zetia® contains the active ingredient ezetimibe which can lower LDL
cholesterol by approximately 20%. It is marketed by Schering-Plough and Merck.
Zocor®
The drug Zocor® contains the active ingredient simvastatin which can lower
LDL cholesterol by approximately 30-40% when taken in standard doses of 20-40 mg per day. Zocor® was the world's fifth best-selling drug
in terms of revenue in 2005. However, it lost its patent protection in 2006 and currently faces
competition with cheaper generic drugs. Zocor® is marketed by Merck.
