Fatal addiction: Britain's 6,200 state-sponsored drug addicts hooked on heroin substitute for more than TEN years Methadone hydrochloride is prescribed to help drug users kick their habit However, many become 'parked' on it and never get completely clean Some patients prescribed substitutes often continue to take heroin as well Other addicts sell their prescribed dose on the black market By Martin Beckford, Stephen Adams and Matthew Davis Thousands of drug addicts have spent more than a decade hooked on a heroin substitute prescribed by the NHS at a cost of £200 million, The Mail on Sunday can reveal. Doctors prescribe the opiate drug methadone hydrochloride to help hard-drug users kick their habit. But in many cases patients simply became "parked" on the replacement and find it even harder to give up. Parked: Intended to be a stepping stone to getting off drugs, to many methadone has simply become a replacement addiction Statistics show more than 6,200 people in England have been taking opiate substitutes non-stop for more than 10 years, while another 27,000 have been prescribed them for longer than five years. Long-term use is rising despite David Cameron declaring in 2010 that methadone was a "government authorised form of opium" that was "not really dealing with the problem." Some addicts sell their prescribed dose on the black market rather than take it, and methadone was linked to 370 deaths last year, twice as many as a decade ago. In fact patients prescribed opioid substitutes often continue to take heroin because methadone does not give them the same high. Critics said long-term prescribing of methadone at an annual cost of £3,000 per patient is wasting billions and urged more should be done to wean patients off the drug. Andrew Griffiths, Conservative MP for Burton and Uttoxeter, uncovered the figures in a Parliamentary question. He said: "This goes to show that the policy of successive governments of state-induced dependency has failed, and the only way to get addicts clean is through abstinence-based rehab." Doctors were originally encouraged to prescribe methadone to tackle the heroin epidemic that hit Britain's inner cities in the 1980s. The intention was to slow the spread of diseases such as HIV/Aids and Hepatitis C by reducing the prevalence of injecting, as well as tackle the crimewave driven by users looking to fund their next fix. Disease: In the 1980s heroin use caused a new public health concern caused by dirty needles spreading HIV/AIDS and Hepatitis C between drug users (picture posed by model) This harm reduction policy was illustrated in the hit 1996 film Train-spotting, in which the main character avoids prison by going on a "state-sponsored addiction" programme of "three sickly sweet doses of methadone a day instead of smack." But in recent years it has exploded with nearly 150,000 addicts being prescribed opioid substitutes -including buprenorphine as well as methadone - at a total cost of £500 million a year. Meanwhile, heroin use has declined, though it is estimated that there are still 300,000 heroin or crack cocaine users in England. The figures show 6,225 people have been taking the drug for more than a decade, up from 4,408 just two years earlier. Another 27,313 have been on it at least five years. Kathy Gyngell, author of a report on methadone for the Centre for Policy Studies, added: "The figures add up to billions of pounds wasted. These people might have come off drugs had they not been kept on methadone, which keeps them dependent on drugs and welfare. But some doctors are adamant that methadone is an appropriate treatment for long-term drug users. Dr Clare Gerada, chairman of the Royal College of GPs, said: "There is a group of patients... for whom methadone provides support for them to live normally." She said some of her patients had such deep-rooted problems that they had been on methadone for more than 20 years. But she added: "We should always try to work towards recovery. There are people who would benefit from rapid access to rehab. Long-term use is most prevalent in the North West. In the Wirral, one in four addicts prescribed a heroin substitute has been taking it for more than 10 years. Fiona Johnstone, Director of Public Health at Wirral Council, said: "Wirral's strategy has resulted in a falling crime rate among users and a very low prevalence of diseases such as HIV and Hepatitis C." Yet plenty of doctors and campaign groups believe it is wrong to keep so many addicted at the taxpayer's expense, rather than helping them get clean. Patients collect a small dose of the green liquid, usually 30 to 50ml, from their pharmacy each morning - 98 per cent do not have to pay for it. Observed: An addict consumes the first of her two daily doses of Methadone under the watchful eyes if a pharmacist (picture posed by models) Some pharmacists insist on watching the patient take it to ensure they do not sell it on - but there is a grim trade in methadone which has been spat out or vomited up later. Dr Peter Swinyard, chairman of the Family Doctor Association and a GP in Swindon, said: "It shouldn't be prescribed unsupported. You need to have backup - a proper team to help addicts with their chaotic lifestyles. Javier Lestacandal, project leader for Teen Challenge, a residential drugs programme, said: "About 80 per cent of people we come across on methadone are using heroin as well. The methadone doesn't resolve the real addiction issue. It's a harm reduction strategy, not a solution. Nick Barton, chief executive of charity Action on Addiction, said: "While heroin substitutes can be an effective treatment on an interim basis, often people are left on it for lengthy periods with no additional psychological support to motivate them to achieve a drug-free life. Current research shows that other forms of treatment may be more cost effective than oral methadone in reducing crime rates. Since the 2010 election, when David Cameron spoke out against methadone in a TV debate, Government drug strategies have aimed at helping more heroin users recover. A report published by the National Treatment Agency last year said that "medication alone is unlikely to be sufficient" to help someone recover. But it warned against imposing strict time limits on how long addicts can remain on methadone. Yet half of councils have had funding for residential drug treatment -seen by many as more effective than methadone - cut in recent years. The NTA's replacement, Public Health England, defended the number of long-term methadone users. Heroin addiction is a chronic, relapsing condition often taking many years to overcome. Being in treatment is protective for individuals - reducing the risk of HIV, blood-borne viruses, and premature death - and brings benefits for families and communities, including reduced offending.