Prescription pattern of codeine for non-malignant pain: a pharmacoepidemiological study from the Norwegian Prescription Database

Opioid prescription for pain relief is increasing. Codeine is the dominating opioid in several European countries, with Norway being among the highest codeine users. To determine whether codeine is primarily used for acute pain or whether there is a prescription pattern indicating problematic opioid use. All pharmacies in Norway are obliged to submit data electronically to the Norwegian Prescription Database at the Norwegian Institute of Public Health on all dispensed prescriptions. Because all prescriptions are identified with a unique person identifier, it is possible to identify all prescriptions to one subject. All subjects who had prescription(s) of codeine dispensed to them in 2004, 2005 or 2006 are included in the study. 385 190 Norwegian persons had at least one prescription of codeine dispensed to them due to non-cancer pain in 2005, corresponding to a 1-year periodic prevalence of 8.3%. 223 778 (58%) received only one prescription in 2005, 121 025 (31%) received more than one prescription but < 120 defined daily doses (DDDs), 30 939 (8%) received between 120 and 365 DDDs, 7661 (2%) between 365 and 730 DDDs, while only 1787 (0.5%) exceeded the maximum recommended dose of 730 DDDs. In the latter group, co-medication with benzodiazepines (65%) and carisoprodol (45%) was prevalent. About one in 10 adult persons in Norway were dispensed codeine in 2005. A majority (58%) received codeine only once, most likely for acute pain, whereas a small minority (0.5%) had a prescription pattern indicating problematic opioid use.