Physical Pharmacy Introduction

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Questions and Answers

Which of the following describes crystalline properties of a drug?

Low order of molecular arrangements

Random molecular arrangements

Zero molecular arrangement

High order of regular molecular arrangements (correct)

What does polymorphism in drugs refer to?

Drug existing in more than one crystal form with varying properties (correct)

Drug's ability to dissolve in water only

Drug being a unique chemical compound

Drug's state of being amorphous

What property indicates the temperature at which a solid substance melts?

Melting point (correct)

Boiling point

Sublimation point

Density point

Which factor does NOT influence drug stability?

Type of packaging Signup and view all the answers

Which process best describes hydrolysis in drug decomposition?

Reaction with water Signup and view all the answers

What is the primary characteristic of an interface?

It is the boundary between two different phases. Signup and view all the answers

What defines surface tension in liquids?

Cohesive forces only accounted for at the surface Signup and view all the answers

What happens to molecules at the surface compared to those in the bulk of a liquid?

They can develop adhesive forces with another phase. Signup and view all the answers

What is the formula used to determine the surface tension of a liquid using the capillary rise method?

γ = ½rpgh Signup and view all the answers

Which of the following methods is primarily used for measuring interfacial tensions?

DuNouy Ring Method Signup and view all the answers

What provides the force necessary to detach the ring in the DuNouy Ring Method?

A torsion wire Signup and view all the answers

What is the correction factor required for accurate results in the DuNouy Ring Method referred to as?

Beta Signup and view all the answers

How do surface-active agents affect surface tension when dispersed in a liquid?

Reduce surface tension Signup and view all the answers

What is the effect of the hydrophobic group in surface-active agents?

Consists of a long carbon chain with low affinity for water Signup and view all the answers

Which of the following claims about surface-active agents is incorrect?

They are uniformly distributed throughout the liquid. Signup and view all the answers

What does the equation γ = Dial reading in dynes / (2 * x * ring circumference) calculate?

Surface or interfacial tension Signup and view all the answers

What is the main focus of studying physicochemical properties in drug formulation?

To understand physical and chemical interactions Signup and view all the answers

Which of the following accurately describes surface tension?

It is influenced by the presence of surfactants. Signup and view all the answers

What is the meaning of critical micelle concentration (CMC)?

The minimum concentration of surfactants needed to form micelles. Signup and view all the answers

What phenomenon describes the process of a substance adhering to a surface?

Adsorption Signup and view all the answers

Which factor does NOT affect adsorption?

Color of the adsorbent material Signup and view all the answers

In rheology, what does the term 'flow behavior' primarily refer to?

The interaction of fluid under stress Signup and view all the answers

Which of the following is NOT a state of matter?

Reversed Signup and view all the answers

What is the primary focus of solubility studies in pharmaceutical applications?

To improve drug dissolution and absorption Signup and view all the answers

What is the primary arrangement of surfactants when forming micelles?

Polar groups directed towards water and non-polar groups directed inward Signup and view all the answers

How does the structure of a surfactant affect its critical micelle concentration (CMC)?

Increasing ethylene oxide chain length increases CMC Signup and view all the answers

What effect does the addition of electrolytes have on ionic surfactants?

Decreases CMC and increases micellar size Signup and view all the answers

What is the typical effect of increasing temperature on nonionic surfactants?

Increases micellar size and decreases CMC Signup and view all the answers

What happens to the micellar properties of ionic surfactants as temperature increases?

There is a small effect until a cloud point is reached Signup and view all the answers

How does the change of counterion affect the micellar size of cationic surfactants?

It causes micellar size to increase Signup and view all the answers

What is the impact of a branched hydrocarbon chain on CMC?

It increases the CMC due to decreased free energy Signup and view all the answers

What describes the cloud point in relation to temperature effects on surfactants?

It signifies the onset of turbidity as two phases separate Signup and view all the answers

What is micellar solubilization primarily used for?

To increase the solubility of materials in a dispersion medium Signup and view all the answers

What must occur before micellar solubilization can take place?

Formation of micelles above the CMC Signup and view all the answers

What does the maximum additive concentration (MAC) represent?

The maximum concentration of a solubilizate that can be incorporated at a fixed surfactant concentration Signup and view all the answers

Which step is necessary for the exact determination of MAC?

Adding concentrations of solubilizates just before turbidity appears Signup and view all the answers

What substance is referred to as the solubilizate?

The hydrophobic substance whose solubility is increased Signup and view all the answers

How does the amount of solubilized material change above the CMC?

It is directly proportional to surfactant concentration Signup and view all the answers

Which of the following is an example of a solubilizate that can increase its solubility through micellar solubilization?

Chloroxylenol in triethanolamine oleate Signup and view all the answers

What happens when turbidity starts to appear during the MAC determination process?

The MAC is reached at that concentration Signup and view all the answers

Study Notes

Course Overview

Introduction to physical pharmacy covers the significance of physicochemical properties in drug formulation over one week.
Key topics include surface and interfacial phenomena, adsorption, rheology, states of matter, solubility, and stability studies.

Surface and Interfacial Phenomena

Surface tension refers to the cohesive forces acting at the surface of a liquid; measuring requires methods like capillary rise.
Surfactants (surface-active agents) reduce surface tension and can form micelles, with specific architectures to minimize water disturbance.
The hydrophilic and hydrophobic characteristics of surfactants dictate their behavior in solutions, influencing micelle formation.

Adsorption

Adsorption involves molecules adhering to surfaces, influenced by types (physisorption and chemisorption) and various factors.
Adsorption isotherms describe the relationship between pressure and the quantity of gas adsorbed.
Boiling and melting points indicate drug stability and influence formulation processes.

Rheology

Fundamental principles define the flow characteristics of substances under stress; important for understanding the behavior of drug formulations.

States of Matter

Matter exists in various states: solids, liquids, and gases, each with unique properties.
Solid properties include crystal forms, polymorphism, and solvation behaviors.

Solubility

Understanding solubility involves types of solutions and factors affecting solubility such as pH and partition coefficients.
Techniques apply partition theory to determine how drugs dissolve and behave in different environments.

Stability Studies

Drug stability is essential for shelf life, influenced by factors including light, heat, and moisture.
Chemical decomposition processes include hydrolysis (e.g., aspirin) and oxidation (e.g., ascorbic acid).

Measuring Surface Tension

Capillary rise calculations help determine surface tension based on liquid density, radius, height, and gravitational pull.
DuNouy tensiometer measures surface/interfacial tensions using forces on a platinum-iridium ring.

Properties of Surface Active Agents (SAAs)

SAAs lower surface and interfacial tension by preferentially adsorbing at interfaces.
They consist of hydrophilic (water-attracting) and hydrophobic (water-repelling) segments, crucial for micelle formation.

Micelles and Solubilization

Micelles spontaneously form, where hydrophobic tails face inward, increasing solubility of hydrophobic substances.
Micellar solubilization leads to enhanced solubility for substances typically insoluble in water, depending on surfactant concentration.

Maximum Additive Concentration (MAC)

MAC refers to the highest concentration of a solubilizate incorporated in a solution above the CMC.
Measurement involves determining where turbidity begins in solutions with increasing solubilizate concentration in fixed surfactant concentrations.

Practical Applications

Surfactants enhance the solubility of compounds like phenolic substances and iodine in formulations, demonstrating significant practical pharmaceutical implications.

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Description

Explore the fundamentals of physical pharmacy, including the significance of physicochemical properties in drug formulation. This quiz covers essential topics such as surface and interfacial tension, surfactants, and measurement techniques. Perfect for students wanting to grasp key concepts in pharmaceutical science.