From Wikipedia,
the free encyclopedia
An excipient is an
inactive substance used as a
vehicle for
medication, or an
active ingredient. In addition
excipients can be used to aid the
process by which a product is
manufactured. In general, the
active substances (such as
aspirin) may not be easily
administered and absorbed by the
human body; they need to be put in
some appropriate form. The active
substance is then dissolved or
mixed with an excipient.
Depending on the
route of administration, and
medication form, various
excipients may be used. For oral
administration, see
Tablets and
Capsules. For rectal
administration see
suppositories.
Once the active ingredient has
been purified, it cannot stay in
purified form for very long. In
many cases it will denature, fall
out of solution, or stick to the
sides of the container. To
stabilize the active ingredient,
excipients will be added to ensure
that the active ingredient stays
active, and is stable for a long
period of time to ensure that the
shelf-life of the product makes it
competitive with other products.
The formulation of these
excipients in many cases is
considered a
trade secret.
Although drugs are chosen
primarily for their active
ingredients, the other ingredients
(excipients) needed to make the
tablet, capsule or liquid are just
as important. For this reason,
excipients are only used when
absolutely necessary and in the
smallest amounts possible.
Types of exipients:
Binders
Binders hold the ingredients in
a tablet together. Binders are
usually
starches,
sugars,
cellulose or modified
cellulose such as
hydroxypropyl cellulose,
lactose, or sugar alcohols
like
xylitol,
sorbitol or
maltitol.
Fillers
Fillers fill out the size of a
tablet or capsule, making it
practical to produce and
convenient for the consumer to
use. Plant cellulose (pure plant
filler) is a popular filler in
tablets or hard gelatin capsules.
Dibasic
calcium phosphate is another
popular tablet filler. Soybean or
safflower oil is used in soft
gelatin capsules.
Disintegrants
Disintegrants expand and
dissolve when wet causing the
tablet to break apart in the
digestive tract, releasing the
nutrients for absorption.
Lubricants
Lubricants prevent ingredients
from clumping together and from
sticking to the tablet punches or
capsule filling machine. Common
minerals like talc or silica, and
fats, e.g. vegetable stearin,
magnesium stearate or stearic acid
are the most frequently used
lubricants in tablets or hard
gelatin capsules.
Coatings
Tablet coatings protect tablet
ingredients from deterioration by
moisture in the air and make large
or unpleasant-tasting tablets
easier to swallow. For most coated
tablets, a cellulose (plant fiber)
film coating is used which is free
of sugar and potential
allergy-causing substances.
Occasionally, other coating
materials are used such as
synthetic polymers, or corn
protein
zein or other
polysaccharides.
Enteric coatings or slow
release coatings control the rate
of drug release, or determine
where the drug will be released in
the digestive tract.
Sweeteners
Sweeteners are added to make
the ingredients more palatable,
especially in chewable tablets or
liquids.
Flavors and Colors
Flavors and Colors are added to
improve the taste or appearance of
a formulation.
Preservatives
Some typical preservatives used
in pharmaceutical formulaitons are
