Podcast
Questions and Answers
Which of the following describes crystalline properties of a drug?
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?
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?
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?
Which factor does NOT influence drug stability?
Which process best describes hydrolysis in drug decomposition?
Which process best describes hydrolysis in drug decomposition?
What is the primary characteristic of an interface?
What is the primary characteristic of an interface?
What defines surface tension in liquids?
What defines surface tension in liquids?
What happens to molecules at the surface compared to those in the bulk of a liquid?
What happens to molecules at the surface compared to those in the bulk of a liquid?
What is the formula used to determine the surface tension of a liquid using the capillary rise method?
What is the formula used to determine the surface tension of a liquid using the capillary rise method?
Which of the following methods is primarily used for measuring interfacial tensions?
Which of the following methods is primarily used for measuring interfacial tensions?
What provides the force necessary to detach the ring in the DuNouy Ring Method?
What provides the force necessary to detach the ring in the DuNouy Ring Method?
What is the correction factor required for accurate results in the DuNouy Ring Method referred to as?
What is the correction factor required for accurate results in the DuNouy Ring Method referred to as?
How do surface-active agents affect surface tension when dispersed in a liquid?
How do surface-active agents affect surface tension when dispersed in a liquid?
What is the effect of the hydrophobic group in surface-active agents?
What is the effect of the hydrophobic group in surface-active agents?
Which of the following claims about surface-active agents is incorrect?
Which of the following claims about surface-active agents is incorrect?
What does the equation γ = Dial reading in dynes / (2 * x * ring circumference) calculate?
What does the equation γ = Dial reading in dynes / (2 * x * ring circumference) calculate?
What is the main focus of studying physicochemical properties in drug formulation?
What is the main focus of studying physicochemical properties in drug formulation?
Which of the following accurately describes surface tension?
Which of the following accurately describes surface tension?
What is the meaning of critical micelle concentration (CMC)?
What is the meaning of critical micelle concentration (CMC)?
What phenomenon describes the process of a substance adhering to a surface?
What phenomenon describes the process of a substance adhering to a surface?
Which factor does NOT affect adsorption?
Which factor does NOT affect adsorption?
In rheology, what does the term 'flow behavior' primarily refer to?
In rheology, what does the term 'flow behavior' primarily refer to?
Which of the following is NOT a state of matter?
Which of the following is NOT a state of matter?
What is the primary focus of solubility studies in pharmaceutical applications?
What is the primary focus of solubility studies in pharmaceutical applications?
What is the primary arrangement of surfactants when forming micelles?
What is the primary arrangement of surfactants when forming micelles?
How does the structure of a surfactant affect its critical micelle concentration (CMC)?
How does the structure of a surfactant affect its critical micelle concentration (CMC)?
What effect does the addition of electrolytes have on ionic surfactants?
What effect does the addition of electrolytes have on ionic surfactants?
What is the typical effect of increasing temperature on nonionic surfactants?
What is the typical effect of increasing temperature on nonionic surfactants?
What happens to the micellar properties of ionic surfactants as temperature increases?
What happens to the micellar properties of ionic surfactants as temperature increases?
How does the change of counterion affect the micellar size of cationic surfactants?
How does the change of counterion affect the micellar size of cationic surfactants?
What is the impact of a branched hydrocarbon chain on CMC?
What is the impact of a branched hydrocarbon chain on CMC?
What describes the cloud point in relation to temperature effects on surfactants?
What describes the cloud point in relation to temperature effects on surfactants?
What is micellar solubilization primarily used for?
What is micellar solubilization primarily used for?
What must occur before micellar solubilization can take place?
What must occur before micellar solubilization can take place?
What does the maximum additive concentration (MAC) represent?
What does the maximum additive concentration (MAC) represent?
Which step is necessary for the exact determination of MAC?
Which step is necessary for the exact determination of MAC?
What substance is referred to as the solubilizate?
What substance is referred to as the solubilizate?
How does the amount of solubilized material change above the CMC?
How does the amount of solubilized material change above the CMC?
Which of the following is an example of a solubilizate that can increase its solubility through micellar solubilization?
Which of the following is an example of a solubilizate that can increase its solubility through micellar solubilization?
What happens when turbidity starts to appear during the MAC determination process?
What happens when turbidity starts to appear during the MAC determination process?
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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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