ABSTRACT
The biological activity of a drug substance is dependent on the nature of the interaction between that drug and the target tissue. However, in order to exert that effect, the drug must be present at the target site in quantities sufficient to elicit the desired response; hence it is essential that the drug be delivered to the appropriate site within the body at the appropriate rate. A large number of dosage forms involve the dispersion of a drug or particles containing drug in a liquid medium; hence it is essential for the formulator to have a knowledge of the science and technology of dispersions. This chapter discusses the use of disperse systems as drug carriers, particularly with a view to controlled drug release and drug targeting. Liposomes attracted interest as potential drug delivery vehicles as it soon became apparent that liposomally entrapped drugs were not distributed and metabolized by cells and tissues in the same manner as the free drugs.
