LONDON - Methadone, the drug prescribed to help heroin addicts break their habit, is helping kill the people it was intended to help. A report by the BBC Panorama programme tonight claims that the heroin substitute is also being sold on the street and used by people who had not previously tried class A drugs. In one small area of the north-east of England 15 people who died from drug over-doses were found to have taken methadone.