A review into the safety and efficacy of OTC codeine-containing medicines reports mixed findings
The Australian review concluded that the drugs do provide significant pain relief but with little evidence of long-term impacts and limited data on adverse events or on rates of abuse or dependency.
In addition, there was mixed evidence on the impact of OTC sales on rates of abuse or dependence.
The TGA review is part of the ongoing investigation on the controversial proposal to reschedule the medicines, deferred late last year.
The review aimed to determine the efficacy and safety of OTC codeine combination analgesics, “for the treatment of any pain conditions” and of OTC codeine-based products as antitussives. The TGA claims the latter is an area which has not previously been systematically evaluated.
One of the significant conclusions they reported were that “a number of studies” found these medicines were “purchased from multiple pharmacies among people with problematic codeine use behaviours”.
“This adds to the challenges of monitoring codeine misuse in the primary care setting,” the authors said.
However one of the studies (from Canada) found a higher proportion of people with codeine dependence had obtained the product from one physician (60%) than from OTC purchases (54%).
The authors said while the majority of studies they examined were overseas they had relevance in an Australian clinical setting.
No placebo controlled trials evaluating the use of codeine combination medicines for headache and back pain could be found, the authors said, despite these conditions being among the most significant reasons for their use, and misuse.
“This review has shown that whilst clinically important pain relief is achieved for the immediate term with combination codeine medicines, none of the studies reported on efficacy outcomes beyond 12 hours, making it difficult to extrapolate efficiency outcomes beyond the immediate term.”
“Combination medicines containing codeine provide clinically significant pain relief for the immediate term following a single dose, however these effects decline after three hours of ingesting the first dose,” the review concluded.
Nausea, tiredness, dizziness and gastrointestinal upset were notably higher in treatment groups compared to placebo, they added.
The release of the TGA review follows the national launch of the Pharmacy Guild of Australia’s MedsASSIST program for real-time recording and monitoring of these medications.
More information on the proposal to reschedule codeine will be published after June 2016, the TGA is now saying on its website.
The review can be accessed here