How to extract pure caffeine from tablets?
The best option would be an organic extraction with dichloromethane. All the other ingredients (except possibly D&amp;C yellow #10 aluminum lake) will be insoluble and therefore unaffected. Filter, let the dichloromethane evaporate and you should have your caffeine.

EDIT: I agree with J M. This caffeine IS NOT EDIBLE. You could easily become intoxicated by the small amounts of dichloromethane that will remain. Also be careful when handling the dichloromethane. Vapors are also toxic and if the liquid is heated or shaken in a closed recipient it might explode. Use caution.