Figure 6.1 Hydrophilic colloid Hydrophilic groups attached to a colloidal particle can help particle stability by adding more repulsion between particles via electrostatic forces. Lyophobic colloids, in contrast (to lyophilic colloids),…
, where V = volume, n = number of moles, R = gas constant, T = temperature, and P = pressure. Consider the liquid state of water: according to the…
Figure 7.1 Illustration of a suspension Typically, suspensions are coarse dispersions consisting of solid particles (100–50000 nm in diameter) in liquid dispersion media. Particles and potential energy To briefly review, when…
Figure 5.1 A simple interaction between a liquid and vapor or air A pure liquid in a container (such as a beaker) with a vapor phase above the bulk liquid. A…
The qualifying statement leads to the following extended definition: ‘If all components are in the same physical state, the component present in the greatest proportion is considered the solvent for…
Scheme 7.1 The spectrum of uses for polymers in pharmaceutics 7.1.1 Definitions Polymers are substances of high molecular weight made up of repeating monomer units. Substances with short chains containing relatively few…
Scheme 3.1 Examples of chemical groups susceptible to hydrolysis. Drugs that contain ester linkages include acetylsalicylic acid, physostigmine, methyldopate, tetracaine and procaine. Ester hydrolysis is usually a bimolecular reaction involving acyl-oxygen…
Figure 4.1 Diagrammatic representation of the three processes involved in the dissolution of a crystalline solute: the expression for the work involved is w22 + w11 − 2w12 (solute–solvent interaction in the last stage is…
Figure 6.1 Photomicrographs of (a) an oil-in-water emulsion and (b) a suspension. Table 6.1 Main types of colloidal systems Type Disperse phase Continuous phase o/w emulsion Oil Water w/o emulsion Water Oil…
Clinical point IA injection of BCNU (carmustine; bis-chloronitrosourea) in the treatment of malignant glioma results in levels of drug that are four times greater than those following IV infusion, but…
