[Transdermal opioid administration: the pain plaster]

A new method of administration of an opioid was recently registered: fentanyl transdermal (brand name: Durogesic), intended particularly for the indication range 'pain in cancer'. Fentanyl is lipid-soluble so that deposition in the skin takes place and the biological half-life is approximately 20 hours after removal of the plaster. It is safe to start on a basis of an equianalgesic conversion of 100:1 in relation to oral morphine, although this may entail some risk of fentanyl under dosage. The dose adjustment time is 12-24 hours before a constant fentanyl level is reached; therefore, after attaching the first sticking plaster, the original morphine dose should be continued for another 12 hours. In addition, the patient may, if necessary, be given supplementary morphine preferably as a short-acting drug. There seems to be no clear indication for transdermal fentanyl either in neuropathic pain or in chronic benign pain.