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POWDERS
POWDERS
A pharmaceutical powders is a mixture of finely
divided drug and chemicals in dry form in a solid
dosage form meant for internal and external use and
available in crystalline (or) amorphous form.
Advantages: Powders are one of the oldest dosage form and are
used both internally and externally.
 Powders are more stable than liquid dosage
form.
 The changes of incompatibility are less as compared
to liquid dosage form.
 Powders are more easy to transport then the liquid
dosage form.
 The onset of action of powdered drug is rapid as
compared to other solid dosage form E.g.tablets,
capsules.
DISADVANTAGES:• Drugs having bitter, nauseous and unpleasant
taste cant be dispensed in powdered form.
• Deliquescent and hydroscopic drugs cant be
dispensed in powder form.
• Drugs which get affected by atmospheric
conditions are not suitable for dispensing in
powder forms.
• Not accurate dosage forms.
CLASIFICATION OF POWDERS
These are mainly classified in to
1.Bulk powder for internal use
2.Bulk powder for external use.
3.Simple and compound powder for internal use
4.Powder enclosed in cachets and capsules.
5. Compressed powders(tablets).
Bulk powder for internal use:• Bulk powder contains several doses of powder.
• They are supplied in wide-mouthed containers that
permits easy removal of a spoonful of powder.
• The non potent substance which are supplied in bulk
are antacids and laxatives etc.
• E.g Rhubarb
Bulk powders external use:• Bulk powder meant for external use are non potent
substance.
• These powders are supplied in cardboard glass or
plastic containers.
• The dusting powders are preferably supplied in
perforated or sifter top containers
• The container should bear a label indicating that the
powder is meant for external application.
The bulk powders which are commonly used
for external applications as follows:-
(a) dusting powders
(b) insufflations
(C) snuffs
(d)dentifrices
Dusting powders:- these are meant for external
application to skin and are generally applied in a
very fine state of sub division to avoid local
irritation .

Hence, dusting powders should be passed
though sieve no 85
dusting powders are of two types:1)medical powders
2)surgical powders
medical dusting powders :- medical dusting
powders are used mainly for superficial skin
condition, where as medical dusting powders
must be free from pathogenic microorganism
surgical dusting powders:- surgical dusting powders
are
used in body cavities and also on major wounds as a result on burns
and umbilical cords of infants.
Surgical dusting powders must be sterilized before their use. Where
as surgical dusting powders must be free from pathogenic
microorganism.
The dusting powders are mainly used for their antiseptic
,astringent, absorbent, antiperspirant, and antipruritic action.
Dusting powders are generally prepared by mixing two or more
ingredients one of which must be either starch ,talk or kaolin as
one of the ingredients of the formulation. Talk and are more
commonly used because these are chemically inert. However,
since such ingredients are readily contaminated with pathogenic
bacteria, these must be sterilized by dry heat method before use .
The dusting powders are dispensed in sifter-top container
or aerosol containers .
Dusting powders may also be applied with powder puff or
sterilized gauze pad.
dusting powders are generally considered to be nontoxic .
Insufflations:-
these are medicated dusting powders
meant for introduction into the body cavities such as nose ,
throat, ears etc; with the help of an apparatus known as
insufflators. It sprays the powder into a stream of finely
divided particles all over the site of application. The following
difficulties of insufflations are
(1)it is difficult to obtain a measured quantity of the drug
as a uniform dose.
(2)It gets blocked when it is slightly wet or the powder used is
wet.
Insufflations should be in finely divided powders so that a
stream of fine particles of medicaments gets applied to the site
application .
Nowadays , the insufflations are available in the form of pressure
aerosols. These are administration of potent drugs. This method
has the advantage of excellent control of dose through metered
valves.
Insufflations are used to produce a local effect ,as in the
treatment of ear ,nose and throat infection with antibiotics.
Snuffs:-these are finely divided solid
dosage forms of
medicament which are inhaled into nostrils for its antiseptic,
bronchodilator and decongestion action.
Snuffs are dispensed in flat metal boxes with hinged lid.
Dentifrices(tooth powders):-these are applied with the
help of a tooth brush for cleaning the surface of the teeth.
they contain a suitable detergent or soap, some abrasive
substance and a suitable flavor.
The abrasive agents such calcium sulphate ,magnesium
carbonate , sodium carbonate and sodium chloride are used
in fine powder. A strong abrasive substance should however
not to be used as it may damage the tooth structure.
Simple and compound powders for internal
use:-In this form of powder ,each individual dose is enclosed
in paper. the number of ingredients may be one or more then
one. the minimum quantity of each powder should not be
less than 100mg so that it can be handled conveniently by
patient and can be weighed accurately
simple powder:-A simple powder contains only one ingredient
either in crystalline or amorphous form .
Eg:-aspirin
compound powders :-compound powders contain two or
more than two substance which are mixed together and then
divided into desired number of individual doses which are
dispersed into each powder paper.
Eg:-compound aspirin powder.
POWDER ENCLOSED IIN CACHTS:-cachets are the
solid unit dosage form of drugs. these are moulded
from rice paper, which is made by pouring a mixture of
rice flour and water between two hot, polished ,
revolving cylinders.
The water evaporates and a sheet of wafer is formed.
cachets are used to enclose nauseous or disagreeable
powders and are available in different sizes to hold
drugs from 0.2to 1.5 of powders.
Cachets are also known as water capsules. They are
quite hard to swallow as such but they are softened by
dipping in water for a few seconds and then placed on
the tongue and swallowed with a draught of water.
After swallowing cachet gets disintegrate and drug is
released.
Advantages of cachets:(1)they can be made easily no complicated machinery is
required.
(2) they disintegrate quickly in the stomach.
(3)the drug can be easily dispensed in cachets.
Disadvantages of cachets:(1)they must be softened before swallowing.
(2)they are easily damaged.
(3)they cannot protect the enclosed drug from light and
moisture.
(4)the shell of cachets are fragile, so the drug contents cannot
be compressed n cachets.
(5)they occupy more space than the corresponding sizes of
capsules and tablets.
Cachets are two types:(a)wet seal cachets
(b)dry seal cachets
(a)wet seal cachets:-a wet seal cachets is made up of
two similar convex halves having flat edges. The
weighted quantity of powdered drug is placed in one
half, the edges of the other half are moistened with
water and placed exactly over the first half containing
the drug. The flat edges of both the halves are
pressed together in order to seal it perfectly.
Dry seal cachets:-dry seal cachets consists of
two halves, the upper half and lower half. The
diameter of the upper half is slightly larger than
the lower half. The powdered drug is filled in
lower half and upper half is fitted over it. the filled
cachets are then sealed in a machine by pressing
the two halves,removd and packed in boxes.
packed and storage of cachets:-the cachets are
packed n boxes or tins in which they are placed
on their edges or lying flat. the container cachets
should be labeled with a direction for its use.
Tablet triturates:-these are powders mounded
into tablets. Mounded tablets are flat , circular disk
and usually contains a potent substance which is mixed
with lactose, dextrose or some other suitable diluents.
Nowadays automatic tablet triturate machine are
available which can prepare 2500 tablet triturates per
minute.
Dispensing of powders involving special
problems:(1) hygroscopic and deliquescent powders:the powders which absorb moisture from the
atmosphere are called hygroscopic powders. but
certain powders absorb moisture to such a great extent
that they go into solution and are called deliquescent
powders.
E,g of such substance include ammonium chloride, iron
and ammonium citrate,pepsin,phenobarbitone,sodium
bromide, sodium iodide, pot citrate, zinc chloride etc.
such substance are usually supplied in granular from
in order to expose less surface area to the atmosphere.
These powders should not be finely powdered. Such
powders should be double wrapped.
(2)Efflorescent powder:-some crystalline
substance liberate water of crystallization wholly or
partly on exposure to humid atmosphere or during
trituration and thus become wet or liquefy.
Eg:-such substance include caffeine, citric acid, ferrous
sulphate etc.
(3)explosive substance:-when an oxidizing
substance, such as pot chloride is mixed with
reducing substance, such as tannic acid are
chance of violet explosion which may lead to
series consequences.
Eg.:-pot chloride, tannic acid, sucrose.
(4) Potent drugs::-the substance having a maximum
dose of less then one grain and poisonous substance are
regarded as the potent drugs, small quantities of potent
drugs should not be weighed on dispensing balance .the
potent drug is triturated with some diluents such as lactose in
definite proportion to make a weighable quantity for each
powder.
Generally potent drug is reduced to fine powder and to this an
equal quantity of diluents is mixed by thought trituration in a
morter,then the rest of diluents is incorporated in successive
portions with thorough trituration each time. the whole of
the diluents should never be added to the drug at one time
otherwise the potent drug will not be mixed uniformly and
thoroughly in the diluents.
E.g:-prednisolone,codeine phosphate
(5)Granular powders:-there are certain solid
medicaments which are required to be administered orally in
large doses .they cannot be prescribed to take as a single
dose, which is not possible .these medicaments are difficult to
dispense as such in powder from because of its bitter,
nauseous and unpleasant taste .it is also difficult to convert it
into liquid dosage form due to stability problem. the only
alternative left is to convert these powdered medicament into
granular form.
(6) Liquids:-in certain prescription, the liquid
medicaments are also incorporated in dispensing
powders. if the quantity of the liquid is small, it may be
triturated with an equal amount of powder, then the
rest of the ingredients are incorporated in small
portion with continuous trituration. If quantities of
liquid are large then an absorbent must be added.
liquid extracts are evaporated to syrup mass in a china
dish. Lactose or some other suitable diluents is mixed
and then continue the evaporation to dryness.mix
other ingredients .another alternative is to substance a
liquid extract by a dry extract.
Inhalation dosage forms
inhalation dosage forma are intended to deliver
drugs to the lungs. the lungs have a large surface area
and a rich blood supply to the alveolar epithelium both
of which favor rapid absorption.
Drugs administered via this route are to affect
pulmonary function or treat allergic symptoms.
example of drugs administered by inhalation include
adrenocorticoidsteroids(beclomethasone),bronchodilat
ors (isoproterenol,metaprotereno,albuterol),and anti
allergic(cromolyn)
administrating drugs via this route is dependent on
factors which involve the formulation, the
administrating device,and the anatomy of the lungs.
Inhalation formulation are generally solution,suspension,and
powders. these formulation are administered via aerosol or a
dry powder inhaler. Aerosols are devices where liquid or
suspension droplets are the internal phase and a gas is the
external phase.
Commercial aerosols are typically metered dose inhaler
(MDI)that deliver a fixed dose in a spray with each actuation
of the device. for compounded inhalation solution ,atomizer,
and vaporizers are the aerosol device.
Commercially available dry powder inhalers contain their
dry powders in manufactured cartridges or disks. when the
patient administers a dose, the devise is first activated by
some mechanical motion and the dry powder becomes ready
for inspiration.
When the patient inhalers through the device
mouthpiece and the powder is drawn into the
pulmonary tract along with the inspired air. these
devices have overcome a major problem of inhalation
therapy, synchronizing deep inspiration with the
administration of the drug. Some of the devices are
Disk haler, turbuhaler, discus, rotahaler.