Powder is a term generally applied to solid substances in small particle size. The particles may be crystalline or amorphous or a resultant of larger particles rendered to a fine state of subdivision.

In the context of dispensing, powders is a class of solid preparations meant for internal or external use containing one or more drugs intimately mixed with each other in a fine state of subdivision.

If necessary, an inert diluent may be added to the potent medicament. Small proportions of volatile constituents- solids or essential oils may also be present.

Historically, powders are the oldest form of presenting a medication. It is perhaps the simplest too, where comparatively little processing and manipulation are involved because most of the basic drugs are marketed in powder form.

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Powders are dispensed in bulk or as individual doses. In the former case, the patient uses sufficient quantity at a time as directed from the bulk supplied to him.

Powders for internal use are dispensed both in bulk as well as in individual doses; however external powders are generally dispensed in bulk excepting sterile powders, which may be dispensed in separate packets.

The packet after opening should be used immediately and another sterile packet is opened when required next time. Sometimes, powders for internal use are not dispensed in fine state of subdivision but are rendered to a granular form by moistening, passing the mass through a sieve and drying.

This form of medication is called granules. The granules are free-flowing and convenient to handle and are generally dispensed in bulk form. Before use, the granules which contain ingredients that react to evolve a gas, when added to water, are called effervescent granules.

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Powders for internal use, in course of time, have been partially replaced by tablets and capsules; however in hospitals powders are still very commonly used.