ABSTRACT
INTRODUCTION Newly discovered lead compounds that are ultimately formulated into drug delivery systems should be capable of existing either in a molecular dispersion, such as solutions or in an aggregate state, such as tablets, capsules, suspensions, and so on that are readily rendered into finer state of dispersion and dissolution. Regardless of the stage of aggregation in the final formulation, the active pharmaceutical ingredient (API) must be released from the drug delivery system and as the first step, should be dissolved in an aqueous environment; this will then be followed possibly by one or more transfers across nonaqueous barriers. The scope of preformulation studies has changed significantly over the past couple of decades with the availability of techniques to study the release and permeation characteristics of lead compounds. Whereas the design of drug delivery systems can alter release characteristics to some extent, the basic permeation characteristics remain an innate property based on the physico-chemical nature of the drug.
