Endocrine and behavioural effects of transdermal buprenorphine in pain-suffering women of different reproductive ages

Chronic pain is a common problem in clinical practice and women are affected more often than men. Morphine is often used for long-term pain relief, but it induces side effects including endocrine alterations. The aim of the present study was to assess the behavioural and hormonal effects of transdermal buprenorphine in women suffering from persistent non-malignant pain. Hormones (LH, FSH, total and free testosterone, estradiol, cortisol) and pain measures (visual analogue scale, McGill Pain questionnaire, present pain intensity test) were evaluated at baseline and after 1, 3 and 6 months. Subjects were recruited in the Second University of Naples Pain Research Centre. Eighteen chronic pain women were included in the study, divided into pre- and post-menopausal groups. A transdermal buprenorphine patch (Buprenorphine TDS, 35 mu g/h) was administered every 72 h. As expected, buprenorphine administration led to a decrease in pain intensity and no side effects suggestive of hypogonadism were recorded. Pain measures decreased at the first control visit (T1) in both groups. Total and free testosterone were not reduced by treatment (they tended to increase in both groups) while cortisol progressively recovered from the quite low levels detected at the beginning of treatment. These data confirm that buprenorphine is a safe and effective drug for pain relief in women. It is free from the adverse effects on gonadal hormones frequently associated with other opioid treatments. The lack of opioid-induced effects on gonadal hormones (i.e. hypogonadism) is important to guarantee safe long-term pain treatment.