ABSTRACT

Dispersed systems are heterogeneous formulations containing insoluble drug particles in aqueous or oil vehicles. Broadly, dispersed systems include suspensions (coarse or colloidal), emulsions, liposomes, and micro-or nanoparticulate systems. Dispersed systems also can be aqueous, nonaqueous, polymeric, or insoluble salt forms/complexes. Reasons why dispersed systems are formulated and marketed are given in Table 9-1. Dispersed systems compose a relatively small segment of the injectable drug product market compared with solutions and freezedried products. However, the most widely used insulin dosage forms (Table 9-2) and several other therapeutic proteins (Table 9-3) are formulated as injectable suspensions. Several important small molecule products and most vaccine products are formulated as dispersed systems (Table 9-4). There is significant growth in the commercialization of dispersed systems used as depot sustained-release injectables (Tables 9-5 and 3-2). Liposomal dispersed system examples are given in chapter 3 (Table 3-3).