POWDERS
Historically, powders represent one
of the oldest dosage forms. They posses some advantages: flexibility in
compounding and relatively good chemical stability. The main disadvantages are
their unsuitability for dispensing unpleasant tasting or hygroscopic drugs and
inaccuracy of dose (for bulk powders).
Classification of powders:
1.
According
to the division into prescribed doses:
Þ bulk powders – all doses are given inseparably (as a
bulk). They may be classified as:
a) oral powders – e.g., antacid and laxative powders
b) dentifrices
c) dusting powders – locally applied nontoxic preparations.
Commercial dusting powders are available in sifter-top containers and pressure
aerosols.
d) insufflations – finely divided powders
introduced into body cavities (ears, nose, throat) with a powder blower
(insufflator). Specialized equipment has been developed for the administration
of micronized powders of relatively potent drugs (e.g., pressure aerosols)
Þ divided powders are divided into the prescribed number of
doses and are given orally. Each individual dose (0.1–1.0 g) should be
transferred to a powder paper.
2. According to the composition:
Þ simplex powders consist of one active
ingredient and suitable inert substances (constituents)
Þ complex powders are mixtures of more than
one active ingredient and constituents.
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