SETTLING IN SUSPENSIONS : One aspect of physical stability in pharmaceutical suspensions is concerned with keeping the particles uniformly distributed throughout the dispersion. It possible to prevent settling completely over a prolonged period of time, it is necessary to consider the […]
Micromeritics is the science and technology of small particles and includes the study of the fundamental and derived properties of individual as well as a collection of particles. The micromeritic properties of a drug can be related in a significant […]
DERIVED PROPERTIES OF POWDERS: There are numerous derived properties that are based on fundamental properties. Those with particular relevance to pharmacy are discussed here. Packing geometry Porosity Density Bulkiness Flow property Packing Geometry: A set of particles can be filled […]
Electric double layer: Particles dispersed in a liquid medium may become charged in one of two main ways. Ionic species present in a solution may be adsorbed at the surface or, alternatively, charges on the surface may arise due to […]
The term ‘rheology’ was derived from the Greek words rheo (flow) and logos (science) and is used to describe the flow of liquids and the deformation of solids. Viscosity is an expression of the resistance of a fluid to flow: […]
Thixotropy: Thixotropy is defined as the progressive decrease in viscosity with time for a constant applied shear stress followed by a gradual recovery when the stress is removed. Thixotropy is a time-dependent shear thinning property. Thixotropy can be defined as […]
STABILITY OF COLLOIDAL SYSTEMS: Colloidal particles undergo frequent collisions as a result of Brownian motion. Whether these collisions result in coagulation (permanent contact or close aggregation of particle), flocculation (temporary contact or large aggregates) or whether the particles rebound and […]
A disperse system is defined as a heterogeneous two-phase system in which the disperse phase is distributed as particles or droplets throughout another phase called as dispersion medium. Based on the size of dispersed particles within the dispersion medium, the […]