Background: Several myths on buprenorphine's pharmacology exist: possible analgesic ceiling effect, feasibility of combination with other opioid agonists, and the reversibility of side effects. Aim to evaluate: 1) if cancer patients receiving high doses of pure agonists could obtain adequate pain relief after switching to transdermal (TD) buprenorphine and 2) whether the numbers of breakthrough pain episodes after switching increased and whether they could be treated with the same doses of pure agonist as before switching.
Design: The prospective open multicenter study included outpatients with moderate-to-severe cancer pain satisfactorily controlled.
Setting: Patients were switched from the usual pure agonist to TD buprenorphine and were titrated to a stable dose. The assessments were: 1) daily self-assessment of pain intensity, numbers of rescue medications, and pain interference with sleep; 2) brief pain inventory; 3) pain relief and pain intensity; 4) quality of life; and 5) adverse events and symptoms.
Results: Eighteen patients receiving 150-516 mg of morphine/day were included. The buprenorphine dose at the end of the study varied between 52.5 and 140 μg/h. No difference in pain before and after switching was shown. The level of rescue doses was maintained. The patches were well tolerated. A significant decrease in fatigue and an increase in global health status were seen after the switch.
Conclusion: It is feasible to switch cancer patients from high doses of pure μ-opioid agonists to TD buprenorphine without eliciting any antagonist effects, but the dose conversion factor is individual and the switching process should be tailored for the individual patient.