Buprenorphine plasma and cerebrospinal fluid concentrations in osteoarthritis patients during low-dose transdermal patch dosing.

METHODS: Fifty-six (56) patients scheduled for arthroplasty, received 7-day extended-release buprenorphine transdermal patches (5 µg/h) for five consecutive weeks, starting two weeks prior to the surgery. Simultaneous plasma and cerebrospinal fluid (CSF) samples were collected during spinal anesthesia. RESULTS: Median buprenorphine plasma and CSF concentrations at steady-state were 54 pg/mL (range 8.6 - 167 pg/mL) and 1.6 pg/mL (0.30 - 7.3 pg/mL), respectively. The median CSF/plasma -ratio was 3% (range 0.35 - 16%). Large between-subject variability was observed in the measured buprenorphine concentrations within the study population.