Vigabatrin (Sabril, Sabrilex) is indicated in the treatment of epilepsy (seizures) only when other conventional therapies are not effective. It is not approved for use in USA but is approved for use in Britain. However it is to be used as 'adjunctive' therapy i.e. to be added to other anti-epileptics (and not to replace other anti-epileptic medicines).
The drug is not approved by the Drugs Controller General, India (DCGI); hence cannot be legally sold by retail chemists. Buying medicines without lawful import, without bills is dangerous since they can be fake. I doubt if the insurance companies in India will reimburse the expenses.
Vigabatrin belongs to a group of drugs called GABA analogue. A similar alternative approved drug in India is called pregabalin (sold under the trade name of Pregab by Torrent). Its normal dose is 50mg three times daily to be increased if required. It costs Rs. 66 for 10 tablets of 75mg each.