[Continuous subcutaneous buprenorphine application in the treatment of cancer pain.]

Introduction Buprenorphine is well known in cancer pain therapy because of the long duration of its action and high analgesic potency. Many studies exist about the intravenous and sublingual application form; however, few data are available on its use by the continuous subcutaneous route. Methods Twenty-five patients were analysed retrospectively over 956 days who has been treated with continuous subcutaneous buprenorphine for cancer-related pain. In 7 of these 25 patients plasma analyses were performed. Due to a modified sensitive HPLC method with electrochemical detection for the analysis of buprenorphine in plasma, a detection limit of 40 pg/ml could be obtained. The other analytical methods for plasma concentration have detection limits between 150 and 500 pg/ml. Results During the treatment with continuous subcutaneous buprenorphine it was necessary to increase the initial average daily dose of 1.07 (+/-0.41) mg to 1.58 (+/-0.58) mg. The initially high pain intensity (rated from 0 to 100%) of 67% could be reduced to a moderate pain of 26% on average. Only 2 patients had to be switched over to morphine because of insufficient analgesia. In no case did complications occur that required intervention or would have made it necessary to change the pain therapy. Eighty percent of the patients judged this kind of treatment as effective and comfortable. Most often patients complained about drowsiness, low appetite and constipation. Because of the progress of the cancer disease these effects could not clearly be related to treatment side effects. With 7 of 25 patients the median daily dose of 1.2 (minimum 0.9-maximum 2.3) mg buprenorphine was related to the median plasma concentration of 438 (minimum 64-maximum 3374) pg/ml. In one case with progressive liver dysfunction, the potential risk of cumulation with buprenorphine could be controlled with this method. Conclusions Continuous subcutaneous buprenorphine with external infusors is a safe and efficient cancer pain therapy without severe side effects. Because of its ceiling effect, it is not as effective as morphine, but can be discussed as an alternative if other opioids cause incompatibility reactions.