Adjuvants Adjuvants are added to vaccines to enhance or modify the immune system response to an immunization. An adjuvant may stimulate the immune system to respond more vigorously to a vaccine, which leads to more robust immunity in the recipient.
Antiadherents Antiadherents reduce the
adhesion between the
powder (
granules) and the
punch faces and thus prevent sticking to tablet punches by offering a
non-stick surface. They are also used to help protect tablets from sticking. The most commonly used is
magnesium stearate.
Antioxidants Antioxidants extend the shelf life of drugs by slowing the degradation of the active ingredient.
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 ether
hydroxypropyl methylcellulose (HPMC) film coating is used which is free of sugar and potential
allergens. Occasionally, other coating materials are used, for example synthetic polymers,
shellac, corn protein
zein or other polysaccharides.
Capsules are coated with gelatin.
Enterics control the rate of drug release and determine where the drug will be released in the digestive tract. Materials used for enteric coatings include fatty acids, waxes, shellac, plastics, and plant fibers.
Colours Colours are added to improve the appearance of a formulation. Colour consistency is important as it allows easy identification of a medication. Furthermore, colours often improve the aesthetic look and feel of medications. Small amounts of colouring agents are easily processed by the body, although rare reactions are known, notably to
tartrazine. Commonly, titanium oxide is used as a colouring agent to produce the popular opaque colours along with azo dyes for other colors. By increasing these
organoleptic properties a patient is more likely to adhere to their schedule and therapeutic objectives will also have a better outcome for the patient especially children.
Controlled release Polymeric additives are used to control the release rate of the active ingredient.
Disintegrants Disintegrants cause the tablet to break apart upon administration. In this way, they release the active ingredients for
absorption. They ensure that when the tablet is in contact with
water, it rapidly breaks down into smaller fragments, facilitating
dissolution. There are three roles identified with lubricants as follows: • True lubricant role: :To decrease friction at the interface between a tablet’s surface and the die wall during ejection and reduce wear on punches and dies. • Anti-adherent role: :Prevent sticking to punch faces or in the case of encapsulation, lubricants. :Prevent sticking to machine dosators, tamping pins, etc. • Glidant role: :Enhance product flow by reducing interparticulate friction. There are two major types of lubricants: • Hydrophilic :Generally poor lubricants, no glidant or anti-adherent properties. • Hydrophobic :Most widely used lubricants in use today are of the hydrophobic category. Hydrophobic lubricants are generally good lubricants and are usually effective at relatively low concentrations. Many also have both anti-adherent and glidant properties. For these reasons, hydrophobic lubricants are used much more frequently than hydrophilic compounds. Examples include magnesium stearate.
Preservatives Some typical
preservatives used in pharmaceutical formulations are •
Antioxidants like
vitamin A,
vitamin E,
vitamin C,
retinyl palmitate, and
selenium • The
amino acids
cysteine and
methionine •
Citric acid and
sodium citrate • Synthetic preservatives like the
parabens:
methyl paraben and
propyl paraben.
Sorbents Sorbents are used for tablet/capsule moisture-proofing by limited fluid sorbing (taking up of a liquid or a gas either by
adsorption or by
absorption) in a dry state. For example,
desiccants absorb water,
drying out (
desiccating) the surrounding materials.
Sweeteners Sweeteners are added to make the ingredients more palatable, especially in chewable tablets such as
antacid or liquids like
cough syrup.
Sugar can be used to mask unpleasant tastes or smells, but artificial sweeteners tend to be preferred, as natural ones tend to cause tooth decay.
Vehicles In liquid and gel formulations, the bulk excipient that serves as a medium for conveying the active ingredient is usually called the
vehicle.
Petrolatum,
dimethyl sulfoxide and
mineral oil are common vehicles. == See also ==