Pharmaceutical Liquid Dispersions Quiz

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Questions and Answers

What is the definition of a dispersed system in pharmaceutical liquid preparation?

The particle distributed is referred to as the dispersed system, and the vehicle is termed the dispersing phase or dispersing medium.

The particle distributed is referred to as the dispersing medium, and the vehicle is termed the dispersed phase.

The particle distributed is referred to as the dispersing phase, and the vehicle is termed the dispersed system.

The particle distributed is referred to as the dispersed phase, and the vehicle is termed the dispersing phase or dispersing medium. (correct)

What type of dispersion has particles in the nanometer range?

Fine dispersion

Coarse dispersion

Molecular dispersion

Colloidal dispersion (correct)

Which type of pharmaceutical mixture is spatially homogeneous and thermodynamically stable?

Solutions (correct)

Particle dispersions (powder blends)

Colloidal dispersions

Liquid dispersions (particles in liquid)

In which pharmaceutical systems are surface chemistry processes important?

Colloidal and dispersed systems Signup and view all the answers

What does the CMC stand for in the context of surfactants?

Critical Micelle Concentration Signup and view all the answers

How does the HLB of a surfactant relate to the contact angle of the solution against a solid?

Lower HLB leads to lower contact angle (better wetting) - True Signup and view all the answers

What does the Gibbs equation describe in relation to surfactants?

Maximum adsorption of surfactants as a monomolecular layer at the L-V interface Signup and view all the answers

What is the relationship between the CMC and the fatty acid chain length of surfactants?

A 2-carbon difference in the fatty acid chain can lead to at least 1 order of magnitude lower CMC Signup and view all the answers

What affects alcohol efficiency in lowering water's $\gamma_{LV}$?

Alkyl chain length Signup and view all the answers

What do nonionic surfactants have?

Uncharged polar head groups Signup and view all the answers

How are surfactants classified based on their polarity?

Using the HLB system Signup and view all the answers

What does lower HLB indicate?

Greater hydrophobicity and better adsorption to surfaces Signup and view all the answers

What does monolayer adsorption on solid surfaces generally lead to?

Monolayers Signup and view all the answers

At what concentration does monolayer adsorption on solid surfaces saturate?

At a given concentration Signup and view all the answers

What does the Gibbs equation describe?

Surface excess of surfactant at a given concentration Signup and view all the answers

When does surface tension lowering cease?

At the critical micelle concentration Signup and view all the answers

What affects micelle formation?

Head and tail structure, counter ions, and temperature Signup and view all the answers

What is used to calculate surface excess and area occupied per molecule for a surfactant?

The Gibbs adsorption equation Signup and view all the answers

What are examples of liquid dispersions in pharmaceutical applications?

Suspensions, emulsions, and foams Signup and view all the answers

What are advantages of liquid dispersions relative to solutions in pharmaceutical applications?

Prolonged chemical stability of the drug, masking poor tasting drugs, ease of swallowing, and administering less soluble drugs in convenient volumes Signup and view all the answers

What are disadvantages of liquid dispersions in pharmaceutical applications?

Non-uniform mixing of particles, floating, agglomeration, and sticking to the container Signup and view all the answers

What are the three general physical instability problems for liquid dispersions?

Non-wetting, aggregation/coalescence, and sedimentation/creaming Signup and view all the answers

What is surface tension (γ) defined as?

The increase in surface free energy per unit area when increasing the surface area, and it correlates with the strength of intermolecular forces Signup and view all the answers

What does interfacial tension of water against immiscible liquids influence?

Wettability of solids Signup and view all the answers

What factors affect contact angle and determine the wetting of solids by liquids?

Young’s Equation Signup and view all the answers

What strategies are involved in improving wetting of solids by liquids?

Lowering γSL, lowering γLV, or raising γSV Signup and view all the answers

What do contact angles of water with various pharmaceutical solids demonstrate?

The varying degrees of wetting for different materials Signup and view all the answers

Study Notes

Liquid Dispersions in Pharmaceutical Applications

Liquid dispersions in pharmaceutical applications include suspensions, emulsions, and foams, which are not spatially homogeneous and are thermodynamically unstable.
Examples of liquid dispersions in pharmaceutical applications are suspensions (solid-in-liquid), emulsions (liquid-in-liquid), and foams (vapor-in-liquid), used for various administration routes.
Advantages of liquid dispersions relative to solutions include prolonged chemical stability of the drug, masking poor tasting drugs, ease of swallowing, and administering less soluble drugs in convenient volumes.
Disadvantages of liquid dispersions include non-uniform mixing of particles, floating, agglomeration, and sticking to the container.
Three general physical instability problems for liquid dispersions are non-wetting, aggregation/coalescence, and sedimentation/creaming, leading to non-uniformity of particle dispersion within the liquid.
H-bonding of water molecules at the surface versus the bulk is an important factor in liquid dispersions.
Surface tension, illustrated by a three-sided wire frame, is the force that must be applied to break the film over the length of the bar in contact with the film.
Surface tension (γ) is defined as the increase in surface free energy per unit area when increasing the surface area, and it correlates with the strength of intermolecular forces.
Interfacial tension (L-L or L-S interface) of water against immiscible liquids and its impact on wettability of solids is influenced by the surface tension.
Factors affecting contact angle, such as Young’s Equation, determine the wetting of solids by liquids.
To promote wetting, certain changes in interfacial area must occur, and strategies to improve wetting involve lowering γSL, lowering γLV, or raising γSV.
Contact angles of water with various pharmaceutical solids demonstrate the varying degrees of wetting for different materials.

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Description

Test your knowledge of liquid dispersions in pharmaceutical applications with this quiz. Explore the advantages and disadvantages of suspensions, emulsions, and foams, and learn about the physical instability problems that can occur. Delve into the factors affecting wetting and the impact of surface tension and interfacial tension on liquid dispersions.