[Non-analgesic effects of opioids]

The aim of the regional administration of opioids is to provide an efficient and prolonged analgesia. Then, opiates can be useful for postoperative analgesia and for the treatment of chronic pain of malignant origin. Analgesia is correlated with several adverse effects of which the most frequent are nausea and itching and the most severe is respiratory depression. Beside the adverse effects, other properties of opiates could be responsible of favourable effects which can be taken in advantage in specific indications. In the postoperative period, epidurally administered opioid can attenuate the neuroendocrine and metabolic responses to surgery and pain. This effect is responsible of a reduction of the resistance to insulin and of a better nutritional balance, especially after major abdominal surgical procedures. Opioids also act by a reduction of the motor functions of the bowel, which perhaps could reduce the incidence of anastomotic breakdowns. Finally, other effects have been reported, as anecdotes, such as the treatment of spasm after bilateral replantation of the ureters, neurologic bladder dysfunctions and enuresis. Spinal administration of opioids has also been used as a treatment of premature ejaculation.