Disulfiram (Esperal) is the specific drug meant for alcoholism. It is not to be used in high blood pressure patients. Naltrexone is actually approved for maintenance therapy for former opioid dependent patients. It is being tried in alcohol dependence (within an overall treatment programme).
You will need to go to a De-Addiction Unit since such drugs are not sold through normal chemist shops and are supplied to psychiatrists directly. Also it is not advisable to use them without intensive medical supervision. There should be a De-Addiction Centre in a large hospital in Gurgaon, if not you can go to AIIMS, New Delhi.