The project aims to probe the relationship between surfactant structure, the micelles formed in solution, and the type of drug molecules that the micelles solubilise. Once obtained this understanding should allow the rational design of novel surfactant molecules to form micelles in which the drug loading is optimized. In the present study a series of structurally related steroidal drug molecules, differing only in the extent of their polarity, namely 4-cholesten-3-one and adrenosterone will be solubilised in 3 types of zwitterionic micelles formed by C12 tailed surfactants. The results of the study will be complemented by molecular dynamic simulations of the drug in the surfactant micelles using the aggregation number obtained from SANS. The results of the study are essential to aiding the rational design and selection of surfactant micelles to optimise drug solubilisation.