Codeine-related poisonings have halved since the drug became prescription-only.

New stats show the rescheduling of all codeine-containing products as prescription-only medications from 1 February 2018 has been associated with a 53 per cent drop in codeine-related presentations at a major Brisbane hospital’s toxicology unit.

A total of 2,235 patients presented to the Princess Alexandra Hospital with poisoning during the 12 months preceding the rescheduling of codeine, and 2,516 during the subsequent 12 months - a 13 per cent increase.

“However, the number of codeine-related presentations was 53% lower during the second period: there were 163 presentations before and 77 presentations after rescheduling,” said a research team, led by Dr Keith Harris, a toxicology and emergency physician at the PAH, and Lecturer at the University of Queensland.

“The numbers of presentations involving 30mg codeine products, the status of which was unaffected by rescheduling, were similar for the two periods (52 before, 60 after rescheduling.

“In contrast, the number of presentations involving codeine products affected by the change (< 30mg) was 85 per cent lower after rescheduling (111 presentations before, 17 presentations after rescheduling). The decline in codeine-related presentations was not associated with a rise in alternative opioid-related presentations (185 alternative opioid-related presentations before, 178 after rescheduling).”

Dr Harris and colleagues also found that about 90 per cent of the products ingested in each period were paracetamol co-formulations.

“In summary, rescheduling of codeine-containing products was associated with a significant reduction in codeine-related presentations to our clinical toxicology unit without the number of alternative opioid-related presentations increasing,” they concluded.

The research is published in the Medical Journal of Australia.