5 5-Diphenylhydantoin sodium salt is a derivative of phenytoin. 5 5-Diphenylhydantoin is used for treating epilepsy and has antiepileptic activity. It functions by blocking the sodium channels and modulates excitation of neurons. However the side effects include hypertrichosis and overgrowth of gum tissue around the teeth. It promotes proliferation of the neural stem cells by modulating growth factors. Diphenylhydantoin is toxic and induces apoptosis in cultured cerebellar granule neurons.