Pharmaceutical Powders and Their Classification

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is a primary disadvantage of sifting when blending powders?

It is time-consuming.

It creates a homogeneous blend.

It requires expensive equipment.

It is not suitable for potent drugs. (correct)

Which method of powder mixing is characterized by being thorough but time-consuming?

Blending with a spatula

Sifting

Tumbling (correct)

Vibration mixing

What phenomenon occurs when fine particles are lifted while larger particles settle at the bottom during blending?

Fluidization

Coalescence

Segregation (correct)

Homogenization

Which method helps prevent segregation during the blending of powders?

Control dust generation. Signup and view all the answers

What is a recommended remedy for hygroscopic powders?

Store in a tight container with desiccant packets. Signup and view all the answers

What type of powder can become sticky or pasty when mixed due to differing melting points?

Eutectic powders Signup and view all the answers

What is the best remedy for deliquescent powders?

Dispense in sealed containers with desiccants. Signup and view all the answers

What should be done with explosive powders to ensure safety?

Store in different containers and avoid mixing. Signup and view all the answers

What is the purpose of trituration in the drug comminution process?

To grind a drug in a mortar to reduce its particle size Signup and view all the answers

Which mortar type is preferred for grinding soft aggregates and crystals in a laboratory setting?

Porcelain Signup and view all the answers

In the levigation process, what is the primary purpose of the levigating agent?

To reduce grittiness of added powders Signup and view all the answers

Which method would be most suitable for blending powdered substances that are particularly potent and available in small amounts?

Geometric dilution Signup and view all the answers

What characterizes the process of pulverization by intervention?

Employing a volatile solvent that can be easily removed post-process Signup and view all the answers

Which statement about spatulation is true?

It is most effective with potent substances in small quantities. Signup and view all the answers

Which of the following is NOT a common equipment used in the levigation process?

Sieve Signup and view all the answers

What is the end product when a levigating paste is combined with an ointment base?

Ointment Signup and view all the answers

Which sieve classification indicates that not more than 40% of the particles can pass through?

Moderately coarse (no.40) Signup and view all the answers

What results from a smaller particle size in terms of dissolution rate?

Higher dissolution rate Signup and view all the answers

Which method of particle size determination uses a mechanical shaker and a series of sieves?

Sieving Signup and view all the answers

What is a key factor affecting the sedimentation rate of particles?

Gravity Signup and view all the answers

Which classification of powder has no limit to greater fineness?

Fine (no.60) Signup and view all the answers

What aspect does lack of grittiness in solid particles affect most directly?

Uniform dosing Signup and view all the answers

What does the light energy diffraction method measure in relation to particle size?

Reduction in light reaching the sensor Signup and view all the answers

Which sieve number indicates that more than 40% of the particles do not pass through?

No.20 Signup and view all the answers

What is the primary characteristic that topical powders must have to avoid skin irritation?

Uniform and small particle size Signup and view all the answers

Which of the following is NOT a disadvantage of powders?

Flexibility in compounding Signup and view all the answers

What does the flowability of a powder refer to?

Ease with which the powder can move or be poured Signup and view all the answers

Which component is commonly used as an adherent in topical powders?

Magnesium stearate Signup and view all the answers

What is the maximum percentage of coarse powders that can pass through a No. 60 sieve?

30% Signup and view all the answers

Which of the following factors is MOST critical for the characterization of a powder?

Particle size Signup and view all the answers

Which type of powder is specifically applied in a body cavity?

Insufflated powders Signup and view all the answers

What is a common composition component that serves as a diluent in topical powders?

Cornstarch Signup and view all the answers

What is the primary purpose of douche powders?

To provide a hygienic and antiseptic effect vaginally Signup and view all the answers

What is a key advantage of granules compared to powders?

Less surface area leading to increased stability against humidity Signup and view all the answers

Which method of granulation is not suitable for moisture and heat sensitive drugs?

Wet granulation using fluid bed processing Signup and view all the answers

What type of paper is recommended for hydroscopic or deliquescent powders?

Waxed paper Signup and view all the answers

Which type of powder can be prepared using the weighing and dividing method?

Divided powders (chartulae) Signup and view all the answers

What is one disadvantage of the wet granulation method?

It is not applicable for moisture and heat sensitive drugs Signup and view all the answers

How are granules generally characterized in terms of particle size?

Mesh size between 4-12 Signup and view all the answers

What is the main advantage of using dry granulation over wet granulation?

It eliminates the steps of wetting and drying Signup and view all the answers

Study Notes

Powders

Intimate mixture of dry, finely divided drugs for both external and internal use.
Serve as limited preparations but are foundational in creating other dosage forms.
Considered the starting point of all dosage forms.

Classification of Powders

Divided based on application: topical powders targeting the skin.
Must have uniform, small particle size to avoid skin irritation.
Characteristics include being impalpable, free-flowing, and able to adhere easily to the skin.
Common compositions include diluents (talc/cornstarch), adherents (magnesium/calcium/zinc stearate), active ingredients, and aromatic materials.
Examples include insufflated powders used with an insufflator for application in body cavities.

Advantages and Disadvantages

Advantages:
- Flexibility in compounding and can be prepared in divided forms.
- Dry, stable, and provide rapid onset of action.
Disadvantages:
- Limited wettability can delay efficacy; inaccurate dosing; unsuitable for dispensing.
- Some powders may be hygroscopic or deliquescent.

Chemical and Physical Characterization

Essential powder characteristics include:
- Particle size and its impact on solubility.
- Solubility, morphology, purity, stability, uniformity, compatibility, and flowability.

Particle Size Analysis

Various types of powder based on particle size analysis include:
- Very Coarse (No.8), Coarse (No.20), Moderately Coarse (No.40), Fine (No.60), Very Fine (No.80).
Chemical origin classifications follow similar particle size categorizations.

Factors Determining Particle Size Classification

Smaller particle sizes lead to higher dissolution rates.
Uniform suspendability promotes consistent dosing.
Adequate penetrability for target organ delivery.
Lack of grittiness in final formulations is crucial.

Methods of Particle Size Determination

Preferred to use multiple methods for accuracy:
- Sieving: Basic method involving mechanical shaking through sieves.
- Microscopy: Uses calibration grids to measure particle size.
- Sedimentation Rate: Based on particles’ settling velocity in a fluid.
- Light Energy Diffraction: Analyzes light blockage to determine size.
- Laser Holography: Advanced imaging technique using lasers.
- Cascade Impaction: Driven particles impacting surfaces by air stream.

Comminution of Drugs

Reduces particle size using methods such as:
- Trituration: Grinding drugs in a mortar, conducted on a small scale.
  - Mortar types: glass (solutions), wedgewood (crystalline solids), porcelain (soft aggregates).
- Levigation: Reduces particle size in ointments using a levigating agent.
- Pulveration by Intervention: Uses volatile solvents for sticky materials.

Blending of Powders

Different techniques for blending include:
- Spatulation: Light compression, suitable for small quantities.
- Trituration: Both comminution and mixing techniques; geometric dilution for potent drugs.
- Sifting: Mixed by passing through sifters but not suitable for potent drugs.
- Tumbling: Mixing in rotating chambers, thorough but time-consuming.

Undesirable Factors in Blending

Segregation: Separation of blend components.
Prevention measures include minimizing transfer steps, controlling dust, managing fluidization, and proper equipment design.

Types of Powders

Eutectic Powders: Become sticky or pasty; remedied with adsorbing powders.
Hygroscopic Powders: Absorb moisture; require storage in tight containers with desiccants.
Deliquescent Powders: Liquefy upon moisture absorption; similar storage requirements as hygroscopic.
Efflorescent Powders: Contain water of crystallization; prefer anhydrous forms.
Explosive Powders: React violently when mixed; should not be combined.

Medicated or Pharmaceutical Powders

Aerosol Powders: Inhaled using devices for quick delivery.
Dusting Powders: Applied on the skin using containers.
Douche Powders: Intended for hygienic vaginal use.
Oral Powders, Detrifices: Mild abrasives for anti-cariogenic purposes.
Insufflation Powders and Trituration Powders: Specific applications for powders.
Divided Powders: Prepared in individual portions using moisture-resistant papers.

Granules

Agglomerates of powdered materials prepared through dry or wet methods.
Payload has a mesh size of 4-12, offering benefits over powders such as better flow, reduced surface area, and ease of wetting.

Methods of Granulation

Wet Granulation: Involves the addition of liquid for binding; effective for improving compressibility and dissolution.
Dry Granulation: Uses high pressure to aggregate particles, suitable for moisture-sensitive drugs, bypassing wetting and drying steps.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore the essential concepts of powders used in pharmaceuticals, including their intimate mixtures for various uses. This quiz covers the classification of powders, focusing on topical powders and their characteristics. Test your knowledge on the starting points of different dosage forms.