People over here have epilepsy, I know a man who's wife suffers with it quite badly. She is on several medications for it, so obviously there is medication for this problem, but maybe you will be given a drug which is similar to what was prescribed in the UK. Find a good English speaking doctor in BG and Im sure he will be able to give her the required prescription for the chemist.
Is your friend coming out here to live, or just for a visit. If its the latter then she should be able to get extra supplies from his/her doctor in UK to cover the vacation.