Displaying 4 results of Modafinil Stable Isotopes Modafinil is a wakefulness-promoting drug used to treat sleep disorders such as narcolepsy. Modafinil stable isotopes are isotopes of modafinil that have a stable nucleus and do not undergo radioactive decay. These isotopes are used in research and development of new drugs and in clinical trials to better understand the pharmacokinetics and metabolism of modafinil. They are also used in the production of modafinil for commercial use.