[Transdermal fentanyl for the treatment of cancer pain.].

Up to 70% of cancer patients in the terminal phase of their disease complain of moderate or severe pain. Pain therapy in these patients follows the analgesic ladder of the WHO. Many cancer patients will need a strong opioid to get sufficient pain relief. Fentanyl-TTS (transdermal therapeutic system) may be a new alternative for chronic pain therapy in cancer patients. Analgesic rates of fentanyl are released from the patch over a period of 72 h. After application, peak serum concentrations of fentanyl are measured after 8-16 h. Serum half-life time is prolonged (16-21 h) because of the intradermal depot of fentanyl. The efficacy of Fentanyl-TTS in pain therapy for cancer patients was demonstrated in clinical studies, which showed a good analgesic effect over a long period of time. Like the chronic therapy of cancer pain with conventional opioid routes, dose escalation was necessary in most patients. In most studies the application of another opioid in a second route of application was necessary as a rescue medication. During therapy of cancer pain with Fentanyl-TTS, 3 of 246 patients developed a bradypnea (respiratory rate <10/min). In contrast, respiratory depression in chronic cancer pain was never reported when the opioid was administered orally or regionally and when technical faults were excluded. The side effects during therapy with Fentanyl-TTS were those accompanying chronic opioid therapy (constipation, vomiting, nausea). The patch was well tolerated by the skin. Local side effects were minor (erythema, pruritus, pustules) and disappeared within a few hours after removal of the patch. The transdermal application of a strong opioid may be an alternative, especially for patients with cancer of the head and neck or in the gastrointestinal tract. Because of the pharmacokinetic laziness of the system the use of Fentanyl-TTS should be limited to patients with stable tumor pain. In these patients Fentanyl-TTS might be valuabe on step III of the analgesic ladder of the WHO or as an alternative to invasive methods when it is impossible to administer oral opioids.