Codeine consumption from over-the-counter anti-cough syrup in Taiwan: A useful indicator for opioid abuse

Over-the-counter (OTC) anti-cough preparations, many of which contain codeine (an opioid) or dextromethorphan (an opioid-like), are widely available in Taiwan and thus susceptible to overuse or abuse. We aimed to investigate whether opioids in the form of OTC antitussives play a significant role in medication abuse in Taiwan.

Data on the consumption of codeine and dextromethorphan in antitussives and expectorants from 2011 through 2014 in Taiwan were provided by IMS Health (Intercontinental Marketing Services). These data were then analyzed for trends and variance according to availability, as prescription or OTC, and according to drug type, as codeine or dextromethorphan, in order to form four primary sectors under opioid-containing anti-cough syrup consumption.

From 2011 to 2014, use of opioid-containing cough syrup fluctuated between 6% and 9% from year to year for all cough syrup consumption, with an overall declining trend (11.3% per year relative to 2011). Within the underlying sectors, mean consumption for prescription dextromethorphan (61.4%) outstripped the other three sectors, followed in decreasing order by OTC codeine (20.2%), OTC dextromethorphan (10.5%), and prescription codeine (8.0%). However, movement in consumption corresponded mainly with OTC codeine, whose variance greatly exceeded that of the other sectors, which follow in order of decreasing variance as OTC dextromethorphan, prescription dextromethorphan, and prescription codeine.

The fairly low and stable consumption of prescription codeine suggested that physicians in Taiwan were careful in prescribing codeine, and that the medical demand for codeine was stable. The large variance in OTC codeine consumption suggested that a minority of consumers purchased significant quantities of codeine for non-medical purposes. Although opioids in cough syrup were not a large part of overall consumption and thus not widely abused, the data revealed that OTC codeine-containing cough syrup may serve as an indicator of potential drug abuse in the population as compared to prescription codeine.