[Lani]

NEW YORK (Reuters Health) Jun 05 - In patients with poorly controlled chronic cancer pain, switching from transdermal buprenorphine to transdermal fentanyl and vice versa allows dose reduction and prompts a significant improvement in analgesic effect, Italian researchers report in a May 7th publication in the Journal of Experimental & Clinical Cancer Research.

"The development of transdermal polymer matrix systems for opioid administration," lead researcher Dr. Caterina Aurilio told Reuters Health, "has resulted in several advantages compared to oral, sublingual or parenteral administration."

"These systems," she added, "represent a non-invasive method, effective and well accepted by cancer patients who often have gastrointestinal problems and difficulties with oral medication."

Dr. Aurilio and colleagues at the Second University of Naples also note that opioid switching is an established method of dealing with unsatisfactory analgesia, and they sought to gain more information on the effect of this strategy in cancer patients receiving transdermal opioids.

The researchers studied 16 patients who were switched from transdermal buprenorphine to transdermal fentanyl, and another 16 patients who were switched from transdermal fentanyl to transdermal buprenorphine. The dosage employed was 50% of that rated as being equipotent.

At three weeks after the start of therapy, both groups had significant improvements in visual analogue pain scores, present pain intensity, and pain rating index scores. There were also significant reductions in use of oral morphine rescue medication and in adverse effects, including constipation and nausea and vomiting. There were no new side effects.

The researchers point out that effective therapy is linked to individual factors, and they call for further studies "to find safe and effective opioid switching methods necessary to give greater insight into the difficult balance between analgesia and toxicity."

J Exp Clin Cancer Res 2009.