Utilisation of transdermal fentanyl in Germany from 2004 to 2006

In our study investigating the utilisation of transdermal fentanyl in Germany, we distinguished between HPO-naïve and HPO-tolerant patients. The former were defined as patients who had not received an HPO during the 3 months preceding the first prescription of transdermal fentanyl. This distinction was based on the definition by the US Food and Drug Administration (FDA) which released a second warning regarding inappropriate use of fentanyl patches in December 2007 after having received reports of life-threatening side effects and fatalities (some related to use of transdermal fentanyl in HPO-naïve patients) to the US spontaneous adverse event reporting system. In this alert, the FDA defined patients as opioid tolerant if they had been using another strong opioid narcotic pain medicine around-the-clock and regularly for a week or longer.1 A similar definition has been used in Canada.2 We used the definition provided by the FDA, since these safety concerns should also hold for Germany. For clarification reasons, we implemented the terms “HPO-naïve” and “HPO-tolerant.” Recommendations in the German Summary of Product Characteristics (SPCs) of transdermal fentanyl products differ substantially depending on year of publication, manufacturer and range of products. Some SPCs (especially those being valid during the time of the study period) put opioid-naïve patients in level with patients who were not treated with strong opioids before3,4 (i.e. our definition of “HPO-naïve”), while others do not distinguish between high-potency and low-potency opioids.5,6 Considering also prior low-potency opioid use, still 15 928 (45.2%) of the patients started on transdermal fentanyl had neither received a low-potency or high-potency opioid before treatment initiation with transdermal fentanyl.