Copyright rules apply 1 of 24 Principles of Disperse Systems (Surface and Interfacial Phenomenon, Colloids and Rheology) Sudip K. Das, MPharm., Ph.D. Professor of Pharmaceutical Sciences References: Remington – The Science and Practice of Pharmacy, 17 th , and 22 nd ed. Martin’s Physical Pharmacy and Pharmaceutical Sciences, Sinko, 6 th ed. Physicochemical Principles of Pharmacy, A T Florence and D Attwood, 6 th ed Pharmaceutics: The Science of Dosage Form Design, M E Aulton, 4th ed Essentials of Physical Chemistry, Bhal, Bhal and Tuli, 2013 Learning Objectives On completion of these topics, the students should be able to Discuss the significance of surface and interfacial phenomena in biological and pharmaceutical systems. Define surface and interfacial phenomenon Define surfactants and their applications in pharmaceutical dosage forms Classify surfactants on the basis of their hydrophile-lipophile balance values. Organize surfactants in different categories Propose ways to enhance the wettability of pharmaceutical powders in liquid media. Apply the principles of surface and interfacial tensions in formulation design Define colloidal dispersion and understand properties of colloids Understand physical properties of lyophilic and hydrophilic colloids Understand electrical properties of colloids Understand application of colloids in pharmaceutical preparations Discuss Newtonian and Non-Newtonian liquids Explain the role of temperature in reducing the viscosity of Newtonian fluids Interpret pseudoplastic and dilatant rheograms and identify shear-thinning and shear-thickening behaviors. Explain the significance of rheology in biological and pharmaceutical systems. Discuss the importance of thixotropy in pharmaceutical systems. Understand rheograms and apply the rheological principles in preparation of a dosage form What is a dispersed system? A relatively stable, homogenous mixture of one phase in another immiscible phase. What are the examples? How do they look like? Why do we need to learn about the dispersed systems? F Y I very soluble drugs: over 1000 mg/ml; freely soluble drugs: 100–1000 mg/ml; soluble drugs: 33–100 mg/ml; sparingly soluble drugs: 10–33 mg/ml; slightly soluble drugs: 1–10 mg/ml; very slightly soluble drugs: 0.1–1 mg/ml; practically insoluble drugs: <0.1 mg/ml. Adapted from Takagi et al. (2006).