Transdermal buprenorphine plus oral paracetamol vs an oral codeine-paracetamol combination for osteoarthritis of hip and/or knee: a randomised trial

Summary Objective Low-dose transdermal opioids offer a new therapeutic option for osteoarthritis (OA). This study compared symptom relief obtained with buprenorphine patches plus oral paracetamol with that obtained with an oral codeine-paracetamol combination tablet (co-codamol) in older adults with OA. Method Two hundred and twenty people (aged ≥60 years) with OA hip and/or knee pain were randomised to treatment with 7-day buprenorphine patches plus oral paracetamol (5–25 μg/h buprenorphine patches plus 1000 mg oral paracetamol q.i.d. (4 times daily); n = 110) or co-codamol tablets (two 8/500–two 30/500 mg tablets q.i.d.; n = 110). They entered a titration period of up to 10 weeks, during which their dose of study medication was adjusted until they reached optimum pain control. Patients who achieved optimum pain control entered a 12-week assessment period. The primary outcome was average daily pain scores recorded using the box scale-11 (BS-11) pain scale. Results Both treatments significantly reduced patient pain scores. The estimated treatment difference [95% confidence interval ( CI)] was −0.02 (−0.64, 0.60) for the per protocol (PP) population. The results were similar for the full analysis population. Patients receiving 7-day buprenorphine patches plus oral paracetamol needed significantly less escape medication (ibuprofen) than those receiving co-codamol tablets ( P = 0.002; PP population). Less than 10% of patients in the 7-day buprenorphine patches plus oral paracetamol group were receiving the highest dose level at the end of the study, compared with 34% in the co-codamol group. Withdrawal rates were high in both groups. The incidence of adverse events (AEs) was comparable between the groups (86.4% of patients in the 7-day buprenorphine patches plus oral paracetamol group; 81.7% in the co-codamol group). Six serious AEs were reported in three patients (2.7%) in the 7-day buprenorphine patches plus oral paracetamol group and one (0.9%) in the co-codamol group. Conclusions 7-day buprenorphine patches plus oral paracetamol were non-inferior to co-codamol tablets with respect to analgesic efficacy in older adults with OA pain in the hip/knee. Clintrials.gov number: NCT00324038.