Dilantin (phenytoin or diphenylhydantoin) is an age-retarding therapy that has received alot of press over the years mainly due to the work of Jack Dreyfus, the founder of the Dreyfus Mutual Funds.  Dreyfus had long suffered from severe depression, which Dilantin cured so successfully that Dreyfus created a medical foundation in order to tell the world about its many benefits.
FDA approval exists only for its use as a treatment for epilepsy.
Dilantin presumably works by its ability to stabilize electrical activity in cell membranes.  Because of this some of the benefits of Dilantin are:
    *  Greater learning ability
    *  Decreased aggression
    *  Enhanced long term memory
    *  Increased Intelligence
    *  Improved verbal performance
Dilantin is also known for helping alcoholism and drug addiction as well as decreasing violent behavior.
Because this drug has been off patent since 1938 there is no attempt by the drug companies to promote the benefits of Dilantin.
Dosage:  Start with 50 to 100 mg in the evening or at bedtime going to no more than 200 mg per day.

The book on Dilantin!