One of Britainâ€™s most commonly used drugs is to be withdrawn over concerns about the high risk of accidental death from slight overdose and its frequent use in suicides, The Times has learnt.
Co-proxamol, prescribed to hundreds of thousands of Britons every year, is to be the subject of a staggered withdrawal because of evidence that it can cause death if patients exceed the maximum recommended dosage by as little as two tablets.
Up to 400 deaths a year are linked to either accidental or intentional overdoses of co-proxamol, which is normally taken for mild to moderate pain and is similar to paracetamol. A recent study found that the medication, whose effects are increased by alcohol, was responsible for 18 per cent of all drug-related deaths and 5 per cent of all suicides. David Kelly, the Governmentâ€™s weapons adviser, is believed to have taken up to three packets of co-proxamol shortly before his death in 2003.
Last year eight million prescriptions were issued in England and Wales for co-proxamol, which has been a mainstay in British healthcare for more than 40 years.
As recently as 1997 it was the second most prescribed drug, after the antibiotic amoxycilin. It is currently marketed by several pharmaceutical companies as co-proxamol and it is also sold under the brand names Distalgesic, Cosalgesic and Dolgesic.
A number of pharmaceutical giants including Eli Lilly, which produced Distalgesic through its subsidiary company Dista, will be affected by the announcement, which will signal the end of a market worth tens of millions of pounds. However, as the patent on co-proxamol has expired and it is now produced in many cheap generic forms, no single company is likely to suffer crippling financial losses.
Patients on co-proxamol, which is used to treat conditions such as mild back pain and arthitis, are recommended not to take more than eight tablets over a 24-hour period. But the ingestion of as few as ten tablets has been linked to overdose and death, often caused by slowing of the respiratory system, abnormal heart rhythms and cardiac arrest.
Co-proxamol is a combination of paracetamol and dextropropoxyphene (DXP), a narcotic related to methadone. Studies have shown that while it is no more effective as pain relief than paracetamol, the odds of dying after a co-proxamol overdose are 28 times higher.
The Times understands that an announcement on the withdrawal of co-proxamol will be made tomorrow by the Medicines and Healthcare products Regulatory Agency (MHRA), the drugs regulator. It has been the subject of an MHRA risk and benefit review since last June. The MHRA is expected to advise that doctors no longer initiate new prescriptions of the drug. Those patients taking co-proxamol should not stop taking it without consulting their doctor. Instead, the MHRA is likely to advise that they should have their prescription changed at their next doctorâ€™s appointment.
While the withdrawal is likely to encounter opposition from some doctors whose patients have enjoyed the benefits of co-proxamol for many years, the MHRAâ€™s decisive move will have strong support from health professionals concerned at the unnecessary risk.
The action is the latest to be taken against high-profile medicines in recent months, after the withdrawal of the antiarthritis drug Vioxx, which had been shown to double the risk of heart attack and stroke.