Pharmaceutical Powders: Definition, Classification and Its Use

Pharmaceutical Powders: Definition, its Classification, Advantages and disadvantages of Powders

Definition of Powders

  • Powders can be applied topically or orally and are intimate combinations of dry, finely separated medicines with or without excipients.
  • A homogeneous mixture of more or less finely divided particulate material in dry form is referred to as a powder.
  • Powders comprise of particles ranging from about 10,000 μ to 0.1 μ.
  • The USP defines powder in terms such as very coarse, coarse, moderately coarse, fine, and very fine depending on their particle size.
  • One of the earliest dose forms, powders can be applied both internally and externally.
  • They provide all patient types with flexibility, stability, rapid therapeutic effect, and ease of administration.
  • However, making powders is not a good method.

What are pharmaceutical powders?

  • A dry, solid substance made up of finely divided drugs, with or without excipients, and intended for internal or external administration is referred to as a pharmaceutical powder.
  • It is a solid material that is often produced by crushing, grinding, or comminating in a finely split form.

Advantages of Pharmaceutical Powders

  • When compared to liquid dose form, powders are more physically and chemically stable.
  • The Pharmaceutical drug product is less susceptible to microbial contamination in powder dose forms.
  • When the dose is quite large, this method of drug delivery is the easiest.
  • For paediatric and geriatric patients powder form is well accepted.
  • There is a large selection of components (ingredients), and determining the dosage for patient administration is simple.
  • The stability of powders is higher than that of liquids
  • A rapid dispersion of medicine happens in the stomach when administrated in powder forms rather than in compressed form.
  • A Powder is easier to swallow and can be easily dissolved in water or another liquid.

Disadvantages of Pharmaceutical Powders

  • Powders are large and bulky pharmaceutical dosage form and creates difficulty in handling and transport of products.
  • Powders as a dosage form may spill and are difficult to transfer from a container.
  • Time consuming procedure to prepare and its packaging.
  • Drugs that have a disagreeable/ unpleasant taste should not be used orally or in powder form.
  • Hygroscopic, acidic pH, deliquescent, volatile and oxygen-sensitive substances used in powder are not suitable to be administered in powder dosage form.
  • Powders are heavy and challenging to transport.

Related: Angle of Repose or Poured Angle for powder flow properties

Classification of powders

The classification of powders is as follows:

  1. Aerosol powders-Insufflations and Dry Powder Inhalers (DPI):
    • Aerosol powders and Insufflations are fine powders of drugs that are inhaled or taken by nose, ear, or throat with the aid of an insufflator or a dry powder inhaler (DPI).
    • The products supplied via this route are meant to treat bronchial problems or such diseases as asthma and chronic obstructive pulmonary disease (COPD).
    • The sizes of the particles supplied by this procedure range from 1 to 6 μm.
    • To protect the powder dosage form, from humidity, improve flow characteristics, and ensure consistent metering, these products also include inert propellants and pharmaceutical diluents.
    • Due to non-uniform dose administration and poor patient compliance, the usage of conventional insufflators has reduced.
    • The conventional insufflators have been replaced by a few newly created devices.
    • Drugs are typically delivered in these devices along with a carrier excipient, like lactose, and put inside a hard gelatin capsule.
    • In DPI operation: When the device is worked, the capsule is broken and the fine pharmaceutical powder is inhaled into the patient’s body.
  2. Bulk powders:
    • Bulk powder medications can only be non-potent compounds.
    • Examples are:
      • Medicated topical anti-infectives,
      • Polymyxin B sulphate,
      • tolnaftate, etc.,
      • Douche powders for vaginal use, such as Massengill powder,
      • Reconstituted Antacid preparations, such as sodium bicarbonate,
      • Laxatives, such as psyllium, etc.
    • A mixture of all the ingredients that has been correctly packaged in a bulk container, like a Pharmaceutical glass or plastic bottle, is referred to as bulk powders.
    • The main disadvantage of Bulk Powder is precision of dosing and it is the main issue with bulk powders.
    • Many variables, such as the measurement tool (spoon), storage humidity, level of settling, and patient variables, might have an impact on the dosage of bulk powders.
    • For instance, depending on the patient’s approach, the dose of bulk powder may range for individuals using spoons of different sizes or even those using the same spoon.
    • A wider therapeutic window, a high dosage, pleasing flavour are also advantages for medications found in bulk powders.
    • Bulk powders with effervescent properties fall under this category.
  3. Divided powders:
    • Bulk powders that have been divided up into individual doses (by using geometric dilution method) are known as divided powders.
    • Examples:
      • Powdered laxatives
      • Douche powder
      • Analgesic powders.
    • Powders that have been separated traditionally come wrapped in paper.
    • However, whether the components are flammable, hygroscopic, or deliquescent, there are other issues associated.
    • As a result, contemporary packaging techniques like foil and plastic laminates are developed to replace the usage of paper wrapping.
    • Powders that are effervescent can be packaged in individual dosages because plastic laminates can prevent moisture absorption.
    • The powdered item must constantly be shielded from contact with moisture.
  4. Effervescent powders or Effervescent salts :
    • When these Effervescent powders are combined with water, carbon dioxide (CO2) is released, causing an effervescence .
    • Additionally, the effervescence aids in reducing the bitter flavour of the active substances.
    • These powders typically contain sodium bicarbonate as well as organic or inorganic acids like citric acid, tartaric acid, etc.
    • Advantages of Effervescent salts:
      • The gastric juices are stimulated by carbon dioxide (CO2), which also speeds up the absorption of several medications.
      • The patient experiences a positive psychological reaction to effervescent salts.
      • Because they are kept in packets with little moisture content, their stability is improved.
  5. Explosive powders:
    • When substances like an oxidising agent and a reducing agent are combined in a mortar and pestle, there is a potential that an explosion could happen owing to the heat generated. This could have significant repercussions.
    • Such powders should be handled by separately triturating each ingredient and gently combining it without exerting any pressure.
    • As an alternative, the powders can be individually triturated, packaged, and administered with the proper usage instructions to the patient.
  6. Medicated powders for internal use:
    • Both internally and externally, these powders are used. Powders for internal usage are either ingested orally or mixed to water.
    • Powders containing internal medications can also be inhaled for systemic or local purposes, such as laxatives or analgesics.
    • Comparing medicated powders to other Solid oral dose formulation (OSD), medicated powders taken systemically will have a faster rate of dissolution and absorption. These powders can also be purchased reconstituted.
  7. Insufflations:
    • Insufflators, a type of applicator, are typically used to apply medicated powders. Insufflations are the introduction of finely divided powder into various body cavities, including the nose, ear, vagina, tooth sockets, etc.
    • A current of air distributes the powder particles in a stream of gas via the nozzle and into the delivery location as the insufflator is compressed. By using insufflations, uniform dosage administration may not be possible.
  8. Dusting powders:
    • Dusting powders are not meant to have a systemic effect; they are used externally for local application. Dusting powders should have below ideal properties:
      • Homogenous & non-irritability
      • Free from local irritation
      • Free-flowing
      • Uniform and good spreading and covering capability
      • Good adsorptive and absorptive capability.
      • Good capacity to protect the skin from chafing (rubbing) and irritation caused by moisture, friction, and chemical irritants.
    • The formulation frequently contains ingredients such as zinc oxide, kaolin, talc, boric acid, and starch.
    • In order to maximise effectiveness and reduce discomfort, dusting powders are typically applied in a relatively fine state (micronized). To enable the powders to be applied to the desired area, dusting powders might be packaged in glass or metal containers with perforated lids.
    • By passing through sieves #85 or 120, these powders are reduced in size. It ought to be distributed ideally in sifter-top containers. These containers offer application simplicity as well as protection from air, moisture, and contamination.
    • It should be marked and Labelled as “FOR EXTERNAL USE ONLY” on the Product label.  
    • Lubricants, protectives, adsorbents, antiseptics, antipruritics, astringents, and antiperspirants are some of the pharmacological categories that are prescribed.
    • The following two categories can be used to categorise dusting powders:
    • Medicated dusting powders: These are bulk powders meant to be administered on the skin that is still in tact for local effect.
    • Surgical dusting powders: These are the bulk powders that are designed to be applied to the skin’s deep layers. As they come into contact with deep layers of the skin and open wounds, these preparations must be sterile.
  9. Dentifrices:
    • Dentifrices are the fine powders (used for external use) that are used to clean teeth. Detergents are added to these powders to give them their cleaning abilities.
    • Along with the detergent, a small quantity of mild abrasive (hydrous dibasic calcium phosphate or precipitated calcium carbonate) mild soap or detergent and sweetening agents are also present.
    • Dentifrices with high abrasive qualities that are unsuitable for everyday usage are typically used by dentists. In these situations, dentists employ pumice powder.
  10. Douche powders:
    • The majority use of this powders, they are applied to the vaginal area with the intention of acting as antiseptics or as cleansing agents.
    • They can also be applied via the ocular or nasal routes. These preparations must meet two basic requirements: they must be thoroughly mixed, and they must preserve the micronized particle size by passing through filter #85.
Douche powders

Related: Incorporation of Ingredients into Pharmaceutical powders, Preparation of Pharmaceutical Powders


Powders are categorized after processing based on their particle size. The USP employs the following descriptive phrases to specify a powder’s particle size:

  1. Very coarse (No. 8) powder: All particles ideally pass through a No. 8 sieve (2.38 mm) and not more than (NMT) 20% pass through a No. 60 sieve.
  • Coarse (No. 20) powder: All particles ideally pass through a No. 20 sieve (0.84 mm) and not more than (NMT) 40% pass through a No. 60 sieve.
  • Moderately coarse (No. 40) powder: All particles ideally pass through a No. 40 sieve (0.42 mm) and not more than (NMT) 40 % pass through a No. 80 sieve.
  • Fine (No. 60) powder: All particles ideally pass through a No. 60 sieve (0.25 mm) and not more than (NMT) 40% pass through a No. 100 sieve.
  • Very fine (No. 80) powder: All particles ideally pass through a No. 80 sieve (0.18 mm). There is no limit to greater fineness.

Similar :Pharmaceutical Powders, powders in pharmaceutics, types of powders in pharmaceutics.



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