Pharmaceutical Suspensions & Powders Lecture Review

A set of 150 practice flashcards covering the definitions, advantages, disadvantages, excipients, and stability of pharmaceutical suspensions based on lecture notes.

What is the definition of a pharmaceutical suspension?

A preparation containing finely divided drug particles distributed throughout a vehicle in which the drug exhibits minimal solubility.

How are drug particles described in a pharmaceutical suspension?

Finely divided drug particles.

In what medium are the drug particles in a suspension distributed?

A vehicle.

What is the solubility requirement for a drug in its suspension vehicle?

It must exhibit minimal solubility.

What is a coarse suspension?

A suspension where particles have a mean diameter $> 1\,\mu m$.

What is a colloidal suspension?

A suspension where particles have a mean diameter $< 1\,\mu m$.

What is the particle size threshold for a coarse suspension?

A mean diameter greater than $1\,\mu m$.

What is the particle size threshold for a colloidal suspension?

A mean diameter less than $1\,\mu m$.

What is a physical disadvantage of pharmaceutical suspensions for patients?

They may be bulky and difficult for the patient to carry.

In terms of thermodynamics, how are suspensions characterized?

They are fundamentally unstable.

For which therapeutic agents are suspensions particularly useful?

Agents that have a low solubility.

How can suspensions be formulated to improve patient experience with bad-tasting drugs?

They may be formulated to mask the taste of therapeutic agents.

Which specific patient population is a target for suspension dosage forms?

Patients who have difficulty swallowing solid dosage forms.

Besides easy swallowing, what is another functional formulation advantage of suspensions?

They may be formulated to provide controlled drug delivery.

According to the properties of a good suspension, how long should it remain uniform?

Long enough for accurate dosing after shaking.

What should happen to the sediment of a good suspension after gentle shaking?

The sediment should redisperse easily.

How should a good suspension flow?

It should flow easily for pouring or removal from the container.

What particle characteristics are required for a smooth and elegant product?

Small, uniform particles.

Name four things affected by particle size control in a suspension.

Rate of sedimentation, texture, ease of use, and bioavailability.

How does particle size control affect the physical feel of the product?

It affects the texture.

How does particle size control affect the rate at which solids sink?

It affects the rate of sedimentation.

How does particle size control affect biological activity?

It affects bioavailability.

What is the objective of using a wetting agent?

To reduce solid-liquid interfacial tension so liquid can replace air on the particle surface.

What does a wetting agent allow the liquid to replace on a particle surface?

Air.

What do wetting agents allow particles to do in the liquid?

Disperse easily.

What is displaced from the crevices of particles by wetting agents?

Air.

List the three categories of wetting agents mentioned.

Hygroscopic liquids, hydrophillic colloids, and surface-active agents.

Give two examples of hygroscopic liquids used as wetting agents.

Glycerin and Propylene glycol.

Is Glycerin used as a wetting agent?

Yes, as a hygroscopic liquid.

Is Propylene glycol categorized as a hygroscopic liquid?

Yes.

List three examples of hydrophillic colloids.

Acacia, Bentonite, and Xantham gum.

How is the name of the gum 'Xanthan' spelled in the transcript for hydrophillic colloids?

Xantham gum.

What is an example of a hydrophillic colloid common to both wetting and suspending agents?

Bentonite.

What is the required HLB value range for surface-active agents used as wetting agents?

Between $7-9$.

What is the primary purpose of a suspending agent?

To increase the viscosity of the dispersion medium.

What do suspending agents prevent?

Rapid settling.

Regarding ease of use, what should a suspending agent NOT do?

Render the suspension too viscous to agitate or to pour.

Regarding drug efficacy, what should a suspending agent NOT do?

Interfere with the availability of the drug.

What are the three main types of suspending/thickening agents?

Natural polysaccharides, water soluble celluloses, and clays.

List five natural polysaccharides used as suspending agents.

Tragacanth powder, Acacia gum, Starch, Agar, and Sodium alginate.

Is Tragacanth powder a natural polysaccharide?

Yes.

Is Acacia gum a type of suspending agent?

Yes, a natural polysaccharide.

Is Sodium alginate classified as a clay?

No, it is a natural polysaccharide.

List two examples of water soluble celluloses.

Methyl cellulose and Sodium carboxymethyl cellulose.

Is Methyl cellulose a polysaccharide or a cellulose?

A water soluble cellulose.

What is Sodium carboxymethyl cellulose used for in suspensions?

As a suspending or thickening agent.

List two examples of clays used as suspending agents.

Bentonite and Aluminium magnesium silicate.

What category of suspending agent does Aluminium magnesium silicate belong to?

Clays.

Is Bentonite used only as a wetting agent?

No, it is also listed as a clay under suspending/thickening agents.

What is the purpose of adding preservatives to a suspension?

To prevent microbial growth and maintain stability.

What miscellaneous excipient is used to mask taste?

Flavourings.

What is the role of sweeteners in a suspension?

To improve the taste of the formulation.

What is the role of colorants?

To provide a desired aesthetic or product identification.

How is the sedimentation rate in a deflocculated suspension?

Slow.

What kind of sediment form is created by deflocculated particles during storage?

A compact cake.

Why is a compact cake a problem in deflocculated suspensions?

It is difficult to redisperse once particles settle.

How is the sedimentation rate in a flocculated suspension?

Fast.

What kind of sediment form is created by flocculated particles?

A loose sediment.

Is flocculated sediment easy or difficult to redisperse?

Easy.

What is a specific dosing risk associated with flocculated suspensions?

Risk of inaccurate dosing if not shaken well.

Why does a flocculated suspension pose a risk of inaccurate dosing?

Due to its fast sedimentation rate.

List three types of flocculating agents.

Electrolytes, polymers, or surfactants.

Can electrolytes be used to maintain suspension stability?

Yes, as flocculating agents.

Can polymers be used as flocculating agents?

Yes.

Can surfactants be used as flocculating agents?

Yes.

What does diagram label 'A' represent in the sedimentation study?

After a few minutes.

What does diagram label 'B' represent in the sedimentation study?

After several hours.

What does diagram label 'C' represent in the sedimentation study?

After prolonged storage.

What is the main goal of using flocculating agents?

To maintain suspension stability.

What does HLB stand for in the context of surface-active agents?

Hydrophile-Lipophile Balance (implied by context of surfactant values).

True or False: Natural polysaccharides are a type of wetting agent.

False, they are listed as suspending/thickening agents.

True or False: A deflocculated suspension has a fast sedimentation rate.

False, it has a slow sedimentation rate.

What property ensures a suspension is smooth and elegant?

Small, uniform particles.

What is another name for a suspending agent?

Thickening agent.

Is Acacia listed as both a hydrophillic colloid and a natural polysaccharide?

Yes (as Acacia and Acacia gum).

What is the effect of suspending agents on the dispersion medium?

They increase the viscosity.

What happens to deflocculated particles after prolonged storage?

They form a compact cake.

What happens to flocculated particles after prolonged storage?

They form loose sediment.

What is the main therapeutic advantage of suspensions for drugs with low solubility?

They allow the drug to be administered in a liquid form despite being insoluble.

How many categories of suspending agents were identified?

Three (Natural polysaccharides, water soluble celluloses, and clays).

Are surfactants used in both wetting and flocculation?

Yes.

What is defined as 'minimal solubility'?

The condition of the drug within the vehicle of a suspension.

What is the primary difference between coarse and colloidal suspensions?

Particle size (diameter).

Why is a high viscosity undesirable for pouring?

It makes the suspension too difficult to remove from the container.

What does it mean for a suspension to be 'fundamentally unstable'?

It is a thermodynamic state where the particles will eventually settle.

Which excipient helps a liquid replace air in particle crevices?

Wetting agent.

What are the specific examples of water soluble celluloses?

Methyl cellulose and Sodium carboxymethyl cellulose.

What specific type of agent is Xantham gum?

Hydrophillic colloid.

Name a clay mentioned in the transcript.

Bentonite.

What type of agent is Aluminium magnesium silicate?

A clay.

Which suspension type forms a 'loose sediment'?

Flocculated suspension.

Which suspension type is difficult to redisperse?

Deflocculated suspension.

Why must a suspension be shaken before use?

To ensure uniform distribution and accurate dosing.

Is Starch a natural polysaccharide?

Yes.

Is Agar a suspending agent?

Yes, specifically a natural polysaccharide.

What do surface-active agents specifically do between $7-9$ HLB?

Act as wetting agents.

Are suspensions bulky?

Yes, this is listed as a disadvantage.

Can a suspension mask the taste of a drug?

Yes.

What is the unit used for particle diameter in the notes?

$\mu m$ (micrometers).

Is Tragacanth powder a clay?

No, it is a natural polysaccharide.