Transdermal fentanyl: Long-term analgesic studies

Alternative routes of drug delivery have particular relevance for use in chronic pain. When the pain experience is constant or nearly constant, a continuous infusion of drug is an ideal way to achieve effective pain relief. Early experience with the transdermal application of fentanyl in chronic cancer pain suggests that it is a safe, noninvasive, effective method of managing pain. The first experience with the use of transdermal fentanyl in cancer pain was reported by Miser and colleagues in 5 patients. They demonstrated that steady-state blood concentrations of fentanyl were linearly related to the transdermal fentanyl dose. The terminal elimination half-life was approximately 34 hr. Zech and colleagues studied 13 patients with chronic cancer pain. Pain relief was obtained and was correlated with plasma fentanyl levels. The largest experience so far was reported in 39 patients in a multicenter trial conducted by Simmonds and colleagues. The median fentanyl dose was 100 μg/hr (range, 25–525 μg/hr). The initial dose of fentanyl from morphine conversion (6:1) was adequate in 50% of patients and titrated upward by 72 hr for the remaining 50%. Patients wore the system for a median of 84 days (range, 5–365 days). Median supplementary daily dose of morphine was 105 mg/day (range, 0–720 mg/day). The system was able to be maintained through a variety of concomitant events. This experience demonstrated the safety and clinical effectiveness of transdermal fentanyl. The transdermal therapeutic system (fentanyl) is a promising advance in achieving noninvasive, continuous drug administration for the management of chronic cancer pain.