Powders are a dosage form in which a medication is presented as a dry, solid, and finely divided substance.
They can be administered internally (e.g., orally, rectally) or externally (e.g., topically).
Powders are prepared by grinding or triturating the solid drug particles until they reach the desired degree of fineness.
Classification of powders
Pharmaceutical powders are solid dosage forms used for drug delivery.
They can be classified based on different criteria, such as particle size, flow properties, or intended use.
Here are some classifications of pharmaceutical powders:
1) Based on particle size:
a) Coarse powder:
Particles with a size range of 355 to 1000 microns.
b) Moderately fine powder:
Particles with a size range of 180 to 355 microns.
c) Fine powder:
Particles with a size range of 75 to 180 microns. d. Very fine powder: Particles smaller than 75 microns.
2) Based on flow properties:
a) Free-flowing powders:
Powders that can flow easily due to low cohesion between particles. These are generally preferred for manufacturing processes.
b) Cohesive powders:
Powders with a tendency to clump or stick together, which can cause issues during manufacturing and require additional processing steps.
3) Based on intended use:
a) Bulk powders:
Intended for direct consumption or as raw materials for the production of other dosage forms like tablets, capsules, or granules.
b) Divided powders:
Pre-weighed and pre-packaged individual doses of the powder, typically used for oral administration.
c) Topical powders:
Applied externally to the skin, mucous membranes, or wounds for therapeutic purposes.
d) Insufflation powders:
Finely ground powders intended for administration through the nasal or respiratory route.
e) Powder for injection:
Sterile, dry powders that are reconstituted with a suitable solvent before being administered via injection.
Advantages of powders:
1) Rapid onset of action:
Due to their fine particle size, powders have a large surface area, which facilitates quick dissolution and absorption.
2) Flexibility in dosing:
Powders can be easily adjusted to provide the appropriate dose for an individual patient.
3) Ease of administration:
Powders can be conveniently mixed with food or drink, making them suitable for patients who have difficulty swallowing solid dosage forms.
4) Stability:
Powders generally have good stability since they are not exposed to moisture or heat, which can degrade some medications.
5) Versatility:
Powders can be formulated for various routes of administration, providing flexibility in meeting patient needs.
Disadvantages of powders:
1) Hygroscopicity:
Some powders can absorb moisture from the air, leading to clumping or degradation of the medication.
2) Taste:
Some medications have an unpleasant taste, which can make powders unpalatable for oral administration.
3) Inaccuracy in dosing:
If not properly divided, powders may result in inaccurate dosing, especially for potent medications.
4) Inconvenience:
Preparing and administering powders can be more time-consuming and less convenient than using other dosage forms, such as tablets or capsules.