Transdermal fentanyl: a new step on the therapeutic ladder.

The high efficacy, low molecular weight and high lipid solubility of fentanyl make it a suitable agent for transdermal administration. Effective plasma concentrations are maintained for up to 48-72 hours after application of a transdermal therapeutic system (TTS) fentanyl patch. In a multicentre study, slow-release morphine was replaced by TTS fentanyl according to a special calculation table (10 mg oral morphine corresponding to approximately 0.1 mg TTS fentanyl). Ninety-eight patients were included in the study. Due to protocol infringements, however, the switch from oral morphine to TTS fentanyl could be assessed for only 38 patients. The changeover at a ratio of 100:1 proved to be safe and effective and a good alternative therapy to conventional strong opioids. The majority of the patients wished to continue TTS fentanyl therapy at the end of the study period. Side effects were similar to those associated with other opioids. However, TTS fentanyl was associated with a distinct decrease in constipation and a significant reduction in the use of laxatives. Furthermore, there were some indications that compliance may be increased with TTS fentanyl. Special indications for chronic pain therapy using transdermal opioids include head and neck and gastro-intestinal tract cancer. In these cases, TTS fentanyl may be the final non-invasive form of analgesic therapy which allows the patient to maintain a normal lifestyle. TTS fentanyl thus represents a new alternative for therapy with strong opioids on step III of the World Health Organization analgesic ladder.