A report this week suggests that enforced restrictions in pack size for paracetamol (acetaminophen) in the UK may have had little or no impact on reducing the number of paracetamol poisonings.
The study, published in the Public Library of Science (PLoS) journal, states that although there was a decline in paracetamol-related poisonings and suicides, there is little evidence to suggest that the drop was due to the restrictions on packaging size.
The restrictions, brought in to reduce the use of paracetamol in deliberate and accidental overdoses, were introduced by the UK Medicines Control Agency in 1998, and limited the size of paracetamol packs to 32 tablets when sold in pharmacies, and 16 tablets from other sellers. 100 tablets could be bought under justifiable circumstances, but voluntary restrictions agreed between the government and the pharmaceutical industry limited the number of tablets to be sold by retailers to 32 tablets in any single transaction.
Although causing quite a stir at the time, and forcing some manufacturers to redesign packaging and even invest in new tooling and machinery, the restrictions were seen by critics as doing little to address the problem of paracetamol-related poisonings and suicides - a consumer could buy additional packs simply walking up the road to another retailer.
The study, carried out by researchers based at Imperial College London in collaboration with the Office for National Statistics in the UK, looked at age-standardised mortality rates for paracetamol poisoning in England and Wales from 1993 to 2004.
While mortality did fall from an average of 212 deaths per year in the five years prior to the legislation, to 154 for the five years after, this decline is put into perspective when compared with deaths caused by a variety of other drugs, as well as 'non-drug' suicides.
Theses other poisoning deaths (involving aspirin, antidepressants and paracetamol compounds as well as non-poisoning suicides), showed similar trends over the time period, even when the drugs had not been restricted.
"This raises the question whether the decline in paracetamol deaths was due to the regulations or was part of a wider trend in decreasing drug-poisoning mortality," the study said.
The researchers themselves come down on the side of a coincidental, rather than causal, relationship between the introduction of the packaging-size restrictions and the drop in paracetamol-related deaths.
Having found "little evidence" that the restrictions caused a greater reduction in poisoning deaths than occurred for other drugs and non-drug poisoning suicides, the study seems to suggest that the legislative moves did little to influence paracetamol poisoning directly, though may have affected its pattern.
A common analgesic used to treat aches and pains, paracetamol is one of the most widely used painkillers and is produced by numerous manufacturers worldwide. In 2006, GlaxoSmithKline (GSK) generated £207m (€306.2m) through its branded Panadol product.
Further information on the research carried out into the impact of paracetamol pack size restrictions can be found here .