An Open-Label Study of the Pharmacokinetics and Tolerability of Once-a-Day Fentanyl Citrate Patch in Japanese Pediatric and Adolescent Patients with Cancer Pain.

BACKGROUND: Transdermal fentanyl is not yet approved for pediatric and adolescent use in Japan. OBJECTIVE: Serum fentanyl concentration and the safety and efficacy of once-a-day fentanyl citrate patch were investigated in pediatric and adolescent patients with cancer pain. METHODS: In this open-label, uncontrolled study, cancer patients aged 2-19 years being treated with strong opioid analgesics were switched to fentanyl citrate patch for 2 weeks. Serum fentanyl concentration was measured at steady state, and severity of pain was evaluated. RESULTS: Eleven patients (four patients aged 2-5 years and seven patients aged 6-19 years) were enrolled. No patient received a dose exceeding 2 mg. Mean serum fentanyl concentrations after administration of 0.5 mg, 1 mg, and 2 mg were 144 pg/mL (n = 4), 277 pg/mL (n = 3), and 2070 pg/mL (n = 4), respectively. All patients were included in the efficacy and safety analysis, but one patient was excluded from the pharmacokinetic analysis because blood was sampled on the day after blood transfusion. A subgroup analysis showed that the mean serum fentanyl concentration tended to be higher in pre-school patients (aged 2-5 years) than in school-aged and adolescent patients (aged 6-19 years) and than in reports of adult patients (aged 20 years and above) who received the same dose. No respiratory adverse events were observed, and pain was well controlled. CONCLUSION: Fentanyl citrate patch tended to result in a higher serum fentanyl concentration in pre-school patients than in school-aged, adolescent, and adult patients who received the same dose. The patch provided adequate pain control, was well tolerated, and did not cause respiratory adverse events. TRIAL REGISTRATION NUMBER: JPRN-JapicCTI-183909.

Efficacy and Safety of Fentanyl Citrate Patch, Including a Low-Dose 0.5 mg Formulation, in Opioid-Naïve Patients with Cancer Pain.

BACKGROUND AND OBJECTIVE: The use of transdermal fentanyl for opioid-naïve patients is restricted, however, transdermal fentanyl is a useful opioid analgesic for patients in whom oral administration is difficult or for those with renal failure. In this study, the efficacy and safety of fentanyl citrate patches was evaluated in opioid-naïve patients suffering from cancer pain. METHODS: An open-label uncontrolled study was conducted in opioid-naïve patients with cancer pain unable to be controlled by non-opioid analgesics. Fentanyl citrate patches starting at a low dose (0.5 mg/patch, corresponding to 6.25 µg/h fentanyl delivered) were applied once/day for up to 14 days. The analgesic effect was assessed every day from the visual analogue scale pain score and the number of doses of rescue medication. When improvement of the analgesic effect was "significant" or "moderate" at a certain dose for three consecutive days, the patient was classified as a "responder" and was considered to have "completed" the study. RESULTS: A fentanyl citrate patch was administered to 208 of 209 enrolled patients. In the full-analysis set, 87.0% of the patients were "responders" (95% confidence interval 81.7-91.3%). In 148 patients, the optimum dose was low (0.5 mg in 99, and 1 mg in 49), with patients finishing the study on days 4-8. Following dose escalation to 4 mg, respiratory depression occurred in one patient; however, this was considered a mild adverse event. CONCLUSION: A low-dose fentanyl citrate patch was effective in the management of cancer pain in opioid-naïve patients and was well tolerated. STUDY REGISTRATION: JPRN-JapicCTI-173717.