CRL-40,940, also known as 4,4′-dilfuoromodafinil, is a eugeroic, and a synthetic analog of modafinil. It acts primarily as a dopamine reuptake inhibitor, and is expected to have stimulant effects in humans. It is a very novel new compound and is undergoing clinical trials in pharmaceutical research.

One study assaying binding affinity of CRL-40,940 (compared to other modafinil analogs) found it to have slightly increased potency over modafinil as a dopamine reuptake inhibitor, with a Ki value of 2190 nM (compared to 2520 nM for modafinil)