Monash University Handbook 2010 Undergraduate - Unit

Synopsis

Solutions, self-assembled systems, multiphase liquid systems and the properties of solids that yield pharmaceutical solutions are key to the performance and manufacture of pharmaceutical products. This unit aims to build on PSC1071 Physical Chemistry II to provide students with a firm understanding of the physical chemistry that underpins the properties and dissolution of pharmaceutical solids and additives to form solutions. In particular an understanding of the physicochemical properties of pharmaceutical solids (drugs and excipients), their transfer into solution form and properties of those solutions from a pharmaceutical science perspective will set the foundation for students to understand the impact of these properties and concepts in pharmaceutical and other formulated products. The key concepts are related directly to aspects of a suite of representative pharmaceutical products allowing the students to put the concepts into a relevant context. The understanding of these principles will also assist students in their understanding in some areas of chemistry, physiology and biology.

This will involve:

• Physical chemistry of solutions
• Solids, semisolids and solubility
• Interfacially active molecules and their use in formulation
• Acid-base functional groups

Objectives

Students will develop an:

1. Understanding of the physicochemical principles that underpin the important processes of pharmaceutical solids dissolving to form a solution. In particular an understanding of dissolution, solubility and distribution are critical in many areas of pharmacy and pharmaceutical science.
2. Understanding of the physical chemistry of solutions once formed will be gained through this unit, including the influence of ionizable functional groups and structure on solution behaviour.
3. Understanding of the behaviour of surface active agents at interfaces and in solution, and how micelles can improve drug solubilization.
4. Understand the physicochemical principles behind the formulation of liquid products, including one and two phase liquid systems.
5. Understanding of the behaviour and properties of pharmaceutical solids and semisolids.
6. Understanding of rheological concepts for fluids
7. Understanding of the role and effect of components (excipients) used to produce solution based dose forms in the pharmacy field.
8. Ability to undertake calculations concerning the physico-chemical properties of drug solutions.
9. Ability to measure fundamental solution properties through practical exercises.

• Describe the various forms of pharmaceutical solids and their impact on drug solution properties.
• Describe the properties of polymers in solution and their rheological aspects.
• Be able to calculate various rheological properties.
• Describe the differences between the terms solution, supersaturation, solubility, solubility parameter, dissolution, distribution (in a physical chemistry sense) and partitioning.
• Describe the factors that influence ideal and non-ideal solubility.
• Describe strategies typically used to improve drug solubility.
• Describe the impact of ionization on partitioning.
• Outline the theories for prediction of drug solubility from solid state properties.
• Calculate changes in solubility with pH for ionisable compounds.
• Calculate and express solution concentrations in molarity, molality, mol fraction and equivalents.
• Describe the physical chemical concepts of solutions of non-electrolytes in terms of vapour pressure, Raoult's Law and Henry's Law.
• Describe the physical chemical concepts of solutions of electrolytes in terms of molar conductivity, Kolrausch's Law, activity and ionic strength.
• Use Kolrausch's Law to calculate molar conductivities using the van't Hoff Factor. Calculate partial pressures for ideal and non-ideal systems given concentrations and activity coefficients. Calculate ionic strength using activity coefficients, Debye Huckel approximation and the extended Debye Huckel theory.
• Outline the common colligative properties and perform simple calculations to quantify these properties.
• Describe the meaning and importance of isotonicity in pharmacy, and perform simple calculations of isotonicity. Describe methods of determination of tonicity of pharmaceutical solutions.
• Describe each component of Fick's first law of diffusion in relation to drug transport across biological membranes.
• Calculate the percentage of ionized and unionized species of an ionizable drug molecule at different pH values and describe the impact of such pH changes on overall drug absorption across a biological membrane.
• Describe the behaviour of surface active molecules at interfaces
• Describe the different classes of surface active molecules and their effect on surface tension
• Describe the location and behaviour of surface active molecules in multiphase systems, particularly emulsions
• Calculate hydrophilic-lipophilic balance, and quantities of surfactants required to form emulsions of a required HLB value.

Assessment

Final exam (3 hour): 70%; written quizzes: 20%; written practical test: 10%.

Chief examiner(s)

Dr Ian Larson

Contact hours

72 contact hours per semester

Additional information on this unit is available from the faculty at:

http://www.monash.edu.au/muso/support/students/browserset.html