TYPES OF DOSAGE FORMS:
Definition:
Dosage forms are the means (or the form) by which drug molecules are delivered to
sites of action with in the body.
The
need for dosage forms:
1-Accurate
dose.
2-Protection
e.g. coated tablets, sealed ampules.
3-Protection
from gastric juice.
4-Masking
taste and odour.
5-Placement
of drugs within body tissues.
6-Sustained
release medication.
7-Controlled
release medication.
8-Optimal
drug action.
9-Insertion
of drugs into body cavities (rectal, vaginal)
10-Use of desired vehicle
for insoluble drugs.
They are classified according to:
Route of administration
|
Physical form
|
Oral
|
Solid
|
Topical
|
Semisolid
|
Rectal
|
liquid
|
Parenteral
|
Gaseous
|
Vaginal
|
|
Inhaled
|
|
Ophthalmic
|
|
Otic
|
ORAL DOSAGE FORMS:
1-Tablet:
A
tablet is a hard, compressed medication in round, oval or square
shape. Solid dosage form containing unit dose of one or more medicament.
-Prepared by mould method or
compression method
The excipients include:
-Binders, glidants (flow
aids) and lubricants to ensure efficient tabletting.
-Disintegrates to ensure that
the tablet breaks up in the digestive tract.
-Sweeteners or flavours to mask
the taste of bad-tasting active ingredients.
Pigments to make uncoated tablets
visually attractive.
1-TABLET (CONT.)
A coating may be applied to:
1-hide
the taste of the tablet's components.
2-make
the tablet smoother and easier to swallow .
3-make
it more resistant to the environment.
4-extending its shelf life.
2-BUCCAL AND SUBLINGUAL TABLET:
Sublingual
and buccal medications are administered by placing the min the mouth, either
under the tongue(sublingual) or between the gum and the cheek (buccal).
The
medications dissolve rapidly and are absorbed through the mucous membranes of
the mouth, where they enter into the bloodstream.
Avoid the acid and enzymatic environment of the stomach and the drug metabolizing enzymes of the liver.
Examples of drugs
administered by this route: e.g. vasodilators, steroidal hormones.
3-EFFERVESCENT TABLET:
Effervescent
tablets are uncoated tablets that generally contain acid substances (citric and
tartaric acids) and carbonates or bicarbonates and which react rapidly in the presence
of water by releasing carbon dioxide.
-They
are intended to be dissolved or dispersed in water before use providing:
A-Very
rapid tablet dispersion and dissolution.
B-pleasant tasting carbonated
drink.
4-CHEWABLE TABLET:
-They
are tablets that chewed prior to swallowing.
-They are designed for administration to
children e.g. vitamin products.
5-CAPSULE:
A capsule
is a medication in a gelatine container.
-solid
dosage form
-Advantage:
mask the unpleasant taste of its contents.
-The
two main types of capsules are:
1-Hard-shelled
capsules, which are normally used for dry, powdered ingredients,
2-Soft-shelled
capsules, primarily used for oils and for active ingredients that are dissolved
or suspended in oil.
6-LOZENGE:
-It
is a solid preparation consisting of sugar and gum, the latter giving strength
and cohesiveness to the lozenge and facilitating slow release of the
medicament.
It
is used to medicate the mouth and throat for the slow administration of
indigestion or cough remedies.
7-PASTILLES
They
are solid medicated preparations designed to dissolves lowly in the mouth. They
are softer than lozenges and their bases are either glycerol and gelatin, or acacia
and sugar.
8-DENTAL CONES:
-A
tablet form intended to be placed in the empty socket following a tooth
extraction, for preventing the local multiplication of pathogenic bacteria
associated with tooth extractions.
-The
cones may contain an antibiotic or antiseptic.
-9-PILLS:
-Pills
are oral dosage forms which consist of spherical masses prepared from one or
more medicaments incorporated with inert excipients.
-Pills
are now rarely used.
10-GRANULES:
They
are consisting of solid, dry aggregates of powder particles often supplied in
single-dose sachets. They are irregular shape particle which are made to
improve flow property of powder
Some
granules are placed on the tongue and swallowed with water, others are intended
to be dissolved in water before taking.
-Effervescent
granules evolve carbon dioxide when added to water.
11-POWDER (ORAL):
----Solid
dosage forms—intimate mixtures of dry finely divided drug or chemicals intended
for internal or external use.
The
mixed powders may be stored in dry form and mixture prepared by the pharmacist
when required for dispensing, by suspending the powders in the appropriate
vehicle.
1-Bulk Powders are multi dose preparations
consisting of solid, loose, dry particles of varying degrees of fineness.—contain
one or more active ingredients, with or without excipients and, if necessary, coloring
matter and flavouring substances.
Usually
contain non potent medicaments such as antacids since the patient measures a dose
by volume using a 5ml medicine spoon. The powder is then usually dispersed in water
or, in the case of effervescent powders, dissolved before taking.
13-LIQUID PREPARATIONS:
a-Oral
solution:
Oral
solutions are clear Liquid preparations for oral use containing one or more
active ingredients dissolved in a suitable vehicle.
b-Oral
emulsion:
Oral
emulsions are stabilized oil-in-water dispersions, either or both phases of
which may contain dissolved solids either oil is dispersed in finely divided
form in water or vice versa
c-Oral
suspension:
-Liquid
preparations for oral use containing one or more active ingredients suspended
in a suitable vehicle.
-may
show a sediment which is readily dispersed on shaking to give a uniform suspension
which remains sufficiently stable to enable the correct dose to be delivered
d-Syrup:
It is a concentrated aqueous solution of a sugar, usually sucrose to which
medicaments are added. Flavored syrups are a convenient form of masking
disagreeable tastes.
13-LIQUID PREPARATIONS (CONT.):
e-Elixir:
-It
is pleasantly flavoured clear liquid oral preparation of potent or nauseous
drugs.
The
vehicle may contain a high proportion of ethanol or sucrose together with
antimicrobial preservatives which confers the stability of the preparation.
f-Linctuses:
--are
viscous, liquid oral preparations that are usually prescribed for the relief of
cough.
--contain
a high proportion of syrup and glycerol which have a demulcent effect on the
membranes of the throat.
The
dose volume is small (5ml) and, to prolong the demulcent action, they should be
taken undiluted.
.
13-LIQUID PREPARATIONS (CONT.):
Oral
Drops:
Oral
drops are Liquid preparations for oral use that are intended to be administered
in small volumes with the aid of a suitable measuring device. They may be
solutions, suspensions or emulsions
h-Gargles:
They
are aqueous solutions used in the prevention or treatment of throat infections.
Usually
they are prepared in a concentrated solution with directions for the patient to
dilute with warm water before use.
i-Mouth
washes:
These
are similar to gargles but are used for oral hygiene and to treat infections of
the mouth.
TOPICAL DOSAGE FORMS:
1-Ointments:
-Ointments are semi-solid,
greasy preparations for application to the skin, rectum or nasal mucosa.
-The base is usually
anhydrous and immiscible with skin secretions.
-Ointments
may be used as emollients or to apply suspended or dissolved medicaments to the
skin.
TOPICAL DOSAGE FORMS (CONT.):
2-Creams:
Creams are semi-solid
emulsions, that is mixtures of oil and water.
They are divided into two
types:
A-oil-in-water (O/W) creams:
which are composed of small droplets of oil dispersed in a continuous aqueous
phase.
Oil-in-water creams are more
comfortable and cosmetically acceptable as they are less greasy and more easily
washed off using water.
B-water-in-oil (W/O) creams:
which are composed of small droplets of water dispersed in a continuous oily
phase.
Water-in-oil creams are more
difficult to handle but many drugs which are in corporate into creams are
hydrophobic and will be released more readily from a water-in-oil cream than an
oil-in-water cream.
Water-in
oil creams are also more moisturising as they provide an oily barrier which
reduces water loss from the stratum corneum, the outer most layer of the skin.
TOPICAL DOSAGE FORMS (CONT.):
3-Gels
(Jellies):
-Gels are semisolid system
in which a liquid phase is constrained with in a 3-D poly meric matrix
(consisting of natural or synthetic gum) having a high degree of physical or
chemical cross-linking.
-They are used for
medication, lubrication and some miscellaneous applications like carrier for
spermicidal agents to be used intra vaginally .
4-Poultice:
It is soft, viscous, pasty preparation
for external use. They are applied to skin while they are hot. Poultice must
retain heat for a considerable time because they are intended to supply warmth
to inflamed parts of body.
E.g.
Kaolin poultice (B.P.C.)
TOPICAL DOSAGE FORMS (CONT.):
5-Pastes
:
-Pastes
are basically ointments into which a high percentage of insoluble solid has
been added
-The
extraordinary amount of particulate matter stiffens the system.
-Pastes
are less penetrating and less macerating and less heating than ointment.
-Pastes
make particularly good protective barrier when placed on the skin, the solid they
contain can absorb and there by neutralize certain noxious chemicals before they
ever reach the skin.
-Like
ointments, paste forms an unbroken relatively water–
Impermeable film unlike ointments the film is opaque
and therefore can be used as an effective sun block accordingly.
TOPICAL DOSAGE FORMS (CONT.):
There
are two types of paste:
a)
Fatty pastes (e.g: leaser's paste) .
b)
Non greasy pastes(e g: - bassorin paste).
6-Dusting
powders:
These
are free flowing very fine powders for external use.
-Not for use on open wounds unless
the powders are sterilized.
TOPICAL DOSAGE FORMS (CONT.):
9-Liniments:
-Liniments
are fluid, semi-fluid or, occasionally, semi-solid preparations intended for
application to the skin.
-They
may be alcoholic or oily solutions or emulsions.
-Most
are massaged into the skin (e.g. counter-irritant).
Liniments should not be applied to broken skin
10-Lotions:
-These are fluid
preparations (aqueous) for external application with out friction—either dabbed
on the skin or applied on a suitable dressing and covered with a waterproof
dressing to reduce evaporation.
TOPICAL DOSAGE FORMS (CONT.):
11-Collodion:
Collodion
is a solution of nitrocellulose in ether or acetone,
sometimes with the addition of alcohols.
Its generic name is
pyroxylin solution.
It is highly flammable.
-As the solvent evaporates,
it dries to a celluloid-like film.
-Compound Wart Remover
consists of acetic acid and salicylic acid in an acetone collodion base used in
Treatment of warts by keratolysis.
TOPICAL DOSAGE FORMS (CONT.):
12-Paints:
Paints
are liquids for application to the skin or mucous membranes.
Skin
paints contain volatile solvent that evaporates quickly to leave a dry resinous
film of medicament.
-Throat paints are more viscous
due to a high content of glycerol, designed to prolong contact of the medicament
with the affected site
TOPICAL DOSAGE FORMS (CONT.):
13-Pressurized
dispensers (aerosol sprays):
Several
different types of pharmaceutical product may be packaged in pressurized
dispensers, known as aerosols.
Surface
sprays produce droplets of 100 um diameter or greater.
May
be used as surface disinfectants, wound or burn dressing, relieve irritation of
bites.
-Spray-on dusting powders
are also available from pressurized containers.
RECTAL DOSAGE FORMS:
1-Suppository:
It is a small solid medicated
mass, usually cone-shaped, that is inserted either into the rectum (rectal suppository),
vagina (vaginal suppository or pessaries) where it melts at body temperature.
RECTAL DOSAGE FORMS (CONT.):
2-Enema:
An enema
is the procedure of introducing liquids into the rectum and colon via the anus.
Types
of enema:
1-Evacuant
enema: used as a bowel stimulant to treat constipation. E.g. soft soap enema &
Mgso4 enema
-The
volume of evacuant enemas may reach up to 2 liters.
-They should be warmed to body
temperature before administration.
RECTAL DOSAGE FORMS (CONT.):
2-Retention
enema:
Their
volume does not exceed 100ml.
No warming
needed.
-May
exert:
A-Local effect: e.g. a barium enema is used as
a contrast substance in the radiological imaging of the bowel.
B-Systemic effect:
e.g.
the administration of substances into the bloodstream. This may be done in situations
where it is impossible to deliver a medication by mouth, such as antiemetics.
e.g. nutrient enema which contains
carbohydrates, vitamins & minerals.
VAGINAL DOSAGE FORMS:
1-Pessary:
Pessaries
are solid medicated preparations designed for insertion into the vagina where
they melt or dissolve.
There
are three types:
A-Moulded
pessaries: they are cone shaped and prepared in a similar way to moulded
suppositories.
B-Compressed
pessaries: made in a variety of shapes and are prepared by compression in a
similar manner to oral tablets.
C-Vaginal
capsules: are similar to soft gelatine oral Capsules differing only in size and
shape.
PARENTERAL DOSAGE FORMS:
An
injection is an infusion method of putting liquid into the body, usually with a
hollow needle and a syringe which is pierced through the skin to a sufficient
depth for the material to be forced into the body.
There
are several methods of injection, including:
1-An
intravenous injection:
It
is a liquid administered directly into the bloodstream via a vein.
It
is advantageous when a rapid onset of action is needed.
PARENTERAL DOSAGE FORMS (CONT.):
2-
Intramuscular injection:
-It is the injection of a
substance directly into a muscle.
-Many vaccines are
administered intramuscularly. -Depending on the chemical properties of the
drug, the medication may either be absorbed fairly quickly or more gradually.
-Intramuscular injections
are often given in the deltoid, vastus lateralis, ventrogluteal and
dorsogluteal muscles.
-Injection
fibrosis is a complication that may occur if the injections are delivered with
great frequency or with improper technique.
PARENTERAL DOSAGE FORMS (CONT.):
3-Subcutaneous
injection:
Subcutaneous
injections are given by injecting a fluid into the sub cutis,
the
layer of skin directly below
the dermis and epidermis.
Subcutaneous injections are
highly effective in administering vaccines and such medications as insulin.
INHALED DOSAGE FORMS:
1-Inhaler
:
Inhalers
are solutions, suspensions or emulsion of drugs in a mixture of inert
propellants held under pressure in an aerosol dispenser.
Release
of a dose of the medicament in the form of droplets of 50 um diameter or less
from the container through a spring-loaded valve incorporating a metering
device. The patient then inhales the released drug through a mouthpiece.
In some
types, the valve is actuated by finger pressure, in other types the valve is actuated
by the patient breathing in through the mouth piece.
It is
commonly used to treat asthma and other respiratory problems.
INHALED DOSAGE FORMS (CONT.):
2-Nebulizer
or (atomizer):
A nebulizer
is a device used to administer medication to people in forms of
a liquid mist to the airways.
-It is commonly used in treating
asthma, and other respiratory diseases.
-It pumps air or oxygen through
a liquid medicine to turn it into a vapor, which is then in haled by the patient.
-As a general rule, doctors generally
prefer to prescribe inhalers for their patients, because:
1-These are cheaper
2-more portable
3-carry less risk of side effects.
Nebulizers, for that reason,
are usually reserved only for serious cases of respiratory disease, or severe attacks.
OPHTHALMIC DOSAGE FORMS:
1-Eye
drops:
Eye
drops are saline-containing drops used as a vehicle to administer
medication in the eye.
Depending on the condition
being treated, they may contain steroids, antihistamines or topical anesthetics.
Eye drops sometimes do not
have medications in them and are only lubricating and tear-replacing solutions.
2-Ophthalmic
ointment & gel:
These are sterile semi-solid
Preparations intended for application
To the conjunctiva or eyelid
margin.
OTIC DOSAGE FORMS:
1-Ear
drops:
Ear
drops are solutions, suspensions or emulsions of drugs that are instilled into
the ear with a dropper.
It
is used to treat or prevent ear infections, especially infections of the outer
ear and ear canal.
NASAL DOSAGE FORMS:
1-Nasal
Drops and Sprays:
Drugs
in solution may be instilled into the nose from a dropper or from a plastic
squeeze bottle.
The
drug may have a local effect, e.g. antihistamine, decongestant.
Alternatively
the drug may be absorbed through the nasal mucosa to exert a systemic effect.
The
use of oily nasal drops should be avoided because of possible damage to the
cilia of the nasal mucosa.
INTERMEDIATE PRODUCTS USED IN COMPOUNDING:
Extracts:
These are concentrated preparations containing the active principals of
vegetable or animal drugs which have been extracted with suitable solvents and
concentrated to form liquid, soft or dry extract.
Glycerins:
These are solutions of medicaments in glycerol with or without the addition of
water.
Infusions:
These are dilute solutions containing the readily soluble constituents of crude
drugs and prepared by diluting 1 part of concentrated infusion with 10 parts of
water. Concentrated infusions are prepared by cold extraction of crude drugs
with 25% ethanol.
INTERMEDIATE PRODUCTS USED IN COMPOUNDING (CONT.):
Oxymels:
These are preparations in which the vehicle is a mixture of acetic acid and
honey.
Spirits:
They are alcoholic or aqueous alcoholic solutions of volatile substances used
as flavouring agents.
Tinctures:
These are alcoholic preparations containing the active principals of vegetable
drugs. They are relatively weak compared to extracts.
Aromatic
waters: These are aqueous solutions, usually saturated of volatile oils or
other volatile substances. Used as flavouring agents.
