General
Description & Use
Orlistat
(XENICAL, Obelit, Alli and Vyfat) also known as tetrahydrolipstatin,
is a drug designed to treat obesity. Its primary function is preventing
the absorption of fats from the human diet, thereby reducing caloric
intake. It is intended for use in conjunction with a physician-supervised
reduced-calorie diet. Orlistat is the saturated derivative of
lipstatin a potent natural inhibitor of pancreatic lipases isolated
from the bacterium Streptomyces toxytricini. However, due to simplicity
and stability, orlistat rather than lipstatin was developed into
an anti-obesity drug.
Orlistat
works by inhibiting pancreatic lipase, an enzyme that breaks down
triglycerides in the intestine. Without this enzyme, triglycerides
from the diet are prevented from being hydrolyzed into absorbable
free fatty acids and are excreted undigested. Only trace amounts
of orlistat are absorbed systemically; the primary effect is local
lipase inhibition within the GI tract after an oral dose. The
primary route of elimination is through the feces.
At the standard prescription dose of 120 mg three times daily
before meals, orlistat prevents approximately 30% of dietary fat
from being absorbed, and about 25% at the standard over-the-counter
dose of 60 mg. Higher doses do not produce more potent effects.
If
you eat an excessive amount of fat or calories, the excess is
stored as fat by the body, resulting in weight gain. When you
eat fat, your body breaks it down into its simplest components
so that it can be digested. Unlike other weight-loss drugs you
may have heard about that act in the brain or central nervous
system to suppress appetite or to speed up metabolism, XENICAL
works in your digestive system to block about one-third of the
fat in the food you eat from being digested.
Enzymes
in your digestive system, called lipases, help digest (or break
down) fat. When taken with meals, XENICAL attaches to the lipases
and blocks them from breaking down some of the fat you have eaten.
The undigested fat cannot be absorbed and is eliminated in your
bowel movements. By working this way, XENICAL helps block about
one-third of the fat in the foods you eat from being absorbed
by your body.
Note:
Due to restrictions we are currently not supplying Meridia (Sibutramine)
Taking XENICAL
The
recommended dose is one 120-mg capsule by mouth with liquid at
each main meal that contains fat. You should take XENICAL up to
three times a day in conjunction with a reduced-calorie diet.
Each time you take XENICAL, your nutritionally balanced meal should
contain no more than about 30% of calories from fat. You should
evenly divide your daily intake of fat, carbohydrates and protein
over three main meals. Take XENICAL during meals or up to 1 hour
after a meal. If you occasionally miss a meal or have a meal without
fat, you can omit your dose of XENICAL. Doses above 120 mg three
times daily have not been shown to provide an additional weight-loss
benefit.
You
should try to follow a healthy eating plan, such as the one developed
by the American Heart Association. Following this eating plan
will help you lose weight while decreasing some of the possible
gastrointestinal effects you may experience while taking XENICAL.
| If
your daily calorie intake is: |
The
recommended daily grams of fat (in a 30% fat diet) are: |
| 1200 |
40 |
| 1400 |
47 |
| 1600 |
53 |
| 1800 |
60 |
| 2000 |
67
|
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your Body Mass Index Now
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XENICAL
interferes with your body's absorption of some fat-soluble vitamins.
Therefore, when you use XENICAL, you should take a daily multivitamin
supplement that contains vitamins D, E, and K and beta carotene.
Take your multivitamin once a day at least 2 hours before or after
taking XENICAL, such as at bedtime.
The
amount of weight loss achieved with orlistat varies. In one-year
clinical trials, between 35.5% and 54.8% of subjects achieved
a 5% or greater decrease in body mass, although not all of this
mass was necessarily fat. Between 16.4% and 24.8% achieved at
least a 10% decrease in body mass. After orlistat was stopped,
a significant number of subjects regained weight - up to 35% of
the weight they had lost. Despite this relatively small body mass
effect, the XENDOS study found a 37% reduction in the incidence
of type 2 diabetes, a significant difference.
Side
effects
The primary side effects of the drug are gastrointestinal-related,
and include steatorrhea... that is, oily, loose stools; because
orlistat blocks some of the dietary fat from being absorbed, the
fat is excreted unchanged in the feces, fecal incontinence, frequent
or urgent bowel movements, and flatulence. GlaxoSmithKline recommends
that Alli users be cautious of the possible side effects until
they "have a sense of any treatment effects". To minimize
these effects, foods with high fat content should be avoided;
the manufacturer advises consumers to follow a low-fat, reduced-calorie
diet. Oily stools and flatulence can be controlled by reducing
the dietary fat content to somewhere in the region of 15 grams
per meal.
According
to Roche, side effects are most severe when beginning therapy
and may decrease in frequency with time; this is supported by
the results of the XENDOS study, which found that only 36% of
people had gastrointestinal adverse effects during their fourth
year of taking orlistat, whereas 91% of study subjects had experienced
at least one GI-related side effect during the first year of treatment.
It has also been suggested that the decrease in side effects over
time may be associated to long-term compliance with a low-fat
diet.
Precautions
Absorption of fat-soluble vitamins and other fat-soluble nutrients
is inhibited by the use of orlistat. A multivitamin tablet containing
vitamins A, D, E, K, and beta-carotene should be taken once a
day, at bedtime, when using orlistat.
XENICAL
shouldn't be taken if you are pregnant, nursing, have food absorption
problems or reduced bile flow. If you are taking cyclosporine,
speak to your doctor before taking XENICAL. XENICAL reduces the
absorption of vitamins, therefore, a daily multivitamin is recommended.
Interactions
Orlistat may reduce plasma levels of ciclosporin (also known as
"cyclosporin" or "cyclosporine", trade names
Sandimmune, Gengraf, Neoral, etc.), an immunosuppressive drug
frequently used to prevent transplant rejection; the two drugs
should therefore not be administered concomitantly. Orlistat can
also impair absorption of the antiarrhythmic amiodarone.
Indication
XENICAL is for people who are considerably overweight (have a
body mass index of 30 or greater). XENICAL is also for people
who are overweight (have a body mass index of 27 or greater) and
also have other risk factors such as high blood pressure, high
cholesterol, heart disease or diabetes. XENICAL should be taken
with a [nutritionally balanced] reduced-calorie diet containing
no more than 30% of calories from fat.
Side
Effects
Because XENICAL works by blocking the absorption of dietary fat,
it is likely that you will experience some changes in bowel habits.
These bowel changes are a natural effect of blocking the fat from
being absorbed. They generally occur during the first weeks of
treatment; however, for some people they may continue for 6 months
or longer while on XENICAL. These changes may include gas with
oily discharge, an increased number of bowel movements, an urgent
need to have them, and an inability to control them, particularly
after meals containing higher amounts of fat than are recommended.
