The amount of paracetamol taken in single overdoses has been reduced by the
introduction of pack size restrictions, pharmacist-led research has found.
In a study published in the British Medical Journal (2000;321:926), Mrs Denise
Robinson (senior pharmacist, regional medicines and poisons information unit,
the Royal hospitals, Belfast) and colleagues assessed the impact of reduced
availability of paracetamol on the number and severity of overdoses. The study
compared cases of self-poisoning in two six-month periods, one before pack size
restrictions were introduced (in September, 1998) and the second period three
months afterwards. It included 590 cases in the first group and 594 in the second.
The researchers found that the estimated quantity of paracetamol ingested fell
from 10g in the first period to 8g in the second. These estimates were associated
with a reduction in paracetamol concentration measurements four to six hours
after the time of poisoning — 37mg/L in the first group compared with 27g/L
in the second group. The percentage of patients given an antidote was also lower
in the second group (25 per cent compared with 31 per cent). There was no change
in the concentration of liver enzymes or the international normalised ratio
at 24 to 48 hours after poisoning.
The researchers comment that overdose behaviour changed after the introduction
of smaller blister packs of paracetamol. The quantity of paracetamol ingested
was reduced and, although there was no change in liver function tests, this
could be explained by early use of antidotes. Pack size restrictions had resulted
in fewer antidotes being given and there were fewer hospital admissions. Both
resulted in a reduction in costs, they say.