Classification of Powders
Bulk powders are nonpotent and can be dosed with acceptable accuracy and safety
using measuring devices such as the teaspoon, cup, or insufflator. This practically
limits the use of orally administered bulk powders to antacids, dietary supplements,
laxatives, and a few analgesics. Many bulk powders are used topically.
Dusting powders are fine medicinal (bulk) powders intended to be dusted on
the skin by means of sifter-top containers. A single medicinal agent may be
used as a dusting powder; however, a base is frequently used to apply a medicinal
agent and to protect the skin from irritation and friction. Bentonite, kaolin,
kieselguhr, magnesium carbonate, starch, and talc are used as inert bases for
dusting powders. Powder bases absorb secretions and exert a drying effect, which
relieves congestion and imparts a cooling sensation. All extemporaneous dusting
powders should be passed through a 100-200 mesh sieve to ensure that they are
grit free and will not further mechanically irritate traumatized areas.
Douche powders are used to prepare solutions that cleanse the vagina. Most
douche powders are used for their hygienic effects, but a few contain antibiotics.
Douche powders are prescribed as a matter of convenience for the patient, since
a powder is more portable than a bulky solution. The formula is developed so
that a teaspoonful or tablespoonful of powder dissolved in a specified volume
of water provides the desired concentration. The pH usually ranges from 3.5
to 5 when the solution is prepared. Feminine bulb syringes or fountain syringes
are used for vaginal irrigation. Since many of the ingredients are volatile
(e.g., menthol, thymol, and volatile oils), douche powders should be packaged
in glass jars with a wide mouth. Some commercial douche powders are available
in metal foil packets, which contain the proper amount of powder for a single
douche. Many douches are also available as prepared unit of use solutions in
Insufflations are extremely fine powders to be introduced into body cavities.
To administer an insufflation, the powder is placed in the insufflator, and
when the bulb is squeezed, the air current carries the fine particles through
the nozzle to the region for which the medication is intended. All extemporaneously
compounded insufflations must be passed through a 100 mesh sieve. Pressurized
packages provide an elegant approach to the administration of insufflations.
In contrast to dusting powders, powders dispensed under pressure will deliver
targeted and uniform application at the desired site. Also, in an aerosol container
medicated powders may be maintained in a sterile condition. The powder particles
must be a definite size range to prevent clogging of the valve orifice and to
provide uniformity of application. In general, powders that are to be packaged
as powder sprays must not contain particles greater than 50 microns if they
are to be sprayed successfully.
Divided Powders (Chartulae; Charts; Powder Papers)
Divided powders or charts are single doses of powdered medicinals individually
wrapped in cellophane, metallic foil, or paper. The divided powder is a more accurate
dosage form than bulk powder because the patient is not involved in measurement
of the dose. Cellophane and foil-enclosed powders are better protected from the
external environment until the time of administration than paper-enclosed powders.Divided
powders are commercially available in foil, cellophane or paper packs.
View a video demonstration on how to fold powder papers