There are drugs out there that (As MandiAnn quite rightly pointed out) have a calming effect on the body. There are a wide range of drugs out there. The one the doctor prescribed me was Valium (I think it was either 5mg or 10mg - I cant remember off the top of my head, its been a while since i used it!). Many seizures are caused by a 'bouncing' electrical current that passes from one side of the brain to the other and back again. (Causing 'hot spots' as my doctor calls them - Parts of the brain that the electrical current can bounce from) Such drugs, as well as slowing the body down, have an effect on the brain which helps to stop this electrical current 'bouncing' and therefore prevents further seizures.
Hope this helps... sorry for the use of jargon! LOL