Research by Professor Keith Hawton and his team at the Oxford Centre for Suicide Research have highlighted the dangers of co-proxamol, leading to its withdrawal.
Co–proxamol (Distalgesic), a combination of an opiate dextropropoxyphene plus paracetamol, is a prescription only painkiller that was widely prescribed in the 1980s and early 1990s. Research by Professor Keith Hawton and his team at the Oxford Centre for Suicide Research has highlighted the dangers of co-proxamol, leading to its withdrawal.
In a study of local suicides between 1993 and 1997 Keith Hawton and his colleagues noticed that co-proxamol was involved in approximately 20% of overdose deaths. The team followed this up with a larger study using national and local data leading to a ground-breaking paper published in the British Medical Journal in 2003. This showed that co-proxamol was the most common drug used for suicide in England and Wales, accounting for 18% of fatalities. They also found that co-proxamol overdoses were 28 times more likely to lead to death than those involving paracetamol. This study prompted the Medicines and Healthcare Products Regulatory Agency (MHRA) and the Committee for the Safety of Medicines (CSM) to take a closer look at co-proxamol in 2004.
At the same time the team performed a study of 123 cases of co-proxamol suicide to determine the circumstances involved. This revealed that in the vast majority of cases (80%) the co-proxamol was prescribed for the individual’s own use, rather than for someone else. It also showed that even relatively small overdoses could prove fatal and that in most cases death occurred before the patient reached hospital.
The results from the Oxford team contributed to the MHRA/CSM review of co-proxamol which led to the recommendation that it should be withdrawn in the UK. Between 2005 and 2007 co-proxamol use was gradually phased out, no new patients were prescribed the drug during this period, and completely withdrawn in 2008. Keith Hawton’s team found that during the withdrawal phase there was a dramatic reduction in co-proxamol overdoses. This was not accompanied by a substantial increase in overdoses involving any other drugs. Deaths due to co-proxamol overdose continued to decrease following the full withdrawal in 2008. In 2012 it was estimated that co-proxamol withdrawal had saved over 600 lives in the UK alone.
This research has had far reaching consequences. As a result of Keith Hawton’s work the European Medicines Agency (EMEA) recommended that dextropropoxyphene, the toxic component of co-proxamol, should not be prescribed within the EU. Subsequently, the authorities in the USA, Canada, New Zealand, Singapore and Taiwan have all acted to withdraw dextropropoxyphene. Keith Hawton’s research and its consequences will no doubt continue to save many lives not just in the UK but also around the world.