As the number of hydrophobic drug development candidates in the pharmaceutical pipeline increases, it is particularly challenging to deliver effective formulations for poorly soluble compounds. Lipid based Liquid Filled Capsule Formulations, and in particular Self-Emulsifying (or Self-Microemulsifying) Drug Delivery Systems (SEDDS/SMEDDS) have been used to enhance the bioavailability of poorly soluble compounds.

These systems typically contain an oil (lipid), surfactants and in some cases a co-solvent. Upon dispersion in an aqueous environment similar to that encountered in the gastrointestinal tract, these systems emulsify under conditions of mild agitation. The primary mechanism of action that leads to higher bioavailability for these formulations is solubilization of the drug (by means of emulsion formation, micellar solubilization or via cosolvency), thus avoiding slow dissolution from the crystalline state, which is frequently the rate limiting step for the absorption of hydrophobic drugs. This leads to overall higher bioavailability, and often reduces variability in absorption.

This presentation will discuss some of the key features of lipid based formulations, considerations for material selection (oils, surfactants, etc.), and the in vitro tools used for formulation characterization, such as phase behavior studies and emulsification tests. Furthermore, comparisons of the in vitro screening tools, such as dispersibility and the in vivo performance of self emulsifying drug delivery systems will be discussed. Examples will be provided to illustrate the effective use of lipid based liquid formulations to support the successful development of challenging poorly water soluble compounds.