There is provided an ex-vivo insect screening model to accurately determine blood-brain barrier penetration of different chemical compounds in order to improve the compound screening procedures/processes in the early drug discovery process. This object offers many advantages relative to prior technologies since insect models are more reliable tools for the decision-making process than the existing in vitro models, and will speed up the drug screening process and reduce the late phase attrition rate. Moreover, it will reduce the number of mammals sacrificed during the drug discovery phase.