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Background: Due to tolerance development and adverse side effects, chronic pain patients frequently need to be switched to alternative opioid therapy, Objective: To assess the efficacy and tolerability of an alternative transdermally applied (TDS) opioid in patients with chronic cancer pain receiving insufficient analgesia using their present treatment., Methods: A total of 32 patients received alternative opioid therapy, 16 were switched from buprenorphine to fentanyl and 16 were switched from fentanyl to buprenorphine. The dosage used was 50% of that indicated in equipotency conversion tables. Pain relief was assessed at weekly intervals for the next 3 weeks, Results: Pain relief as assessed by VAS, PPI, and PRI significantly improved (p < 0.0001) in all patients at all 3 follow up visits. After 3 weeks of treatment, the reduction in the mean VAS, PPI, and PRI scores in the fentanyl and buprenorphine groups was 68, 77, 74, and 69, 79, and 62%, respectively. Over the same time period the use of oral morphine as rescue medication was reduced from 27.5 +/- 20.5 (mean +/- SD) to 3.75 +/- 8.06, and 33.8 +/- 18.9 to 3.75 +/- 10.9 mg/day in the fentanyl and buprenorphine groups, respectively. There was no significant difference in either pain relief or rescue medication use between the two patient groups The number of patient with adverse events fell during the study. After the third week of the treatment the number of patients with constipation was reduced from 11 to 5, and 10 to 4 patients in the fentanyl and buprenorphine groups, respectively. There was a similar reduction in the incidence of nausea and vomiting. No sedation was seen in any patient after one week of treatment., Conclusion: Opioid switching at 50% of the calculated equianalgesic dose produced a significant reduction in pain levels and rescue medication. The incidence of side effects decreased and no new side effects were noted. Further studies are required to provide individualized treatment for patients according to their different types of cancer.

The neurobiology of pain had a notable interest in research focused on the study of neuronal plasticity development, nociceptors, molecular identity, signaling mechanism, ionic channels involved in the generation, modulation and propagation of action potential in all type of excitable cells. All the findings open the possibility for developing new therapeutic treatment. Nociceptive/inflammatory pain and neuropathic pain represent two different kinds of persistent chronic pain. We have reviewed the different mechanism suggested for the maintenance of pain, like descending nociceptive mechanism and their changes after tissue damage, including suppression and facilitation of defence behavior during pain. The role of these changes in inducing NMDA and AMPA receptors gene expression, after prolonged inflammation is emphasized by several authors. Furthermore, a relation between a persistent pain and amygdale has been shown. Molecular biology is the new frontier in the study of neurobiology of pain. Since the entire genome has been studied, we will able to find new genes involved in specific condition such as pain, because an altered gene expression can regulate neuronal activity after inflammation or tissue damage., (Copyright 2006 Wiley-Liss, Inc.)

The Aim: of this study was to evaluate the effectiveness and the safety of the association of buprenorphine transdermal delivery system (TDS) (Transtec TDS) and peridural infusion of morphine and naropine, for the control of ischemic pain in patients suffering from peripheral arteriopathy. The administration of an opioid, pure agonist, as morphine, with a partial agonist opioid, as the buprenorphine, was used. Buprenorphine has shown a higher liposolubility in supraspinal districts, while the morphine acts above all on the mu receptor subtype of the spinal cord. In this way it's possible a contemporary activation of spinal and supraspinal antinociceptive mechanisms. Furthermore, the incidence of side effects is reduced by buprenorphine, which antagonizes the central effect of morphine. In this study, 43 patients were recruited, suffering from chronic pain in Fontaine stage III-IV obstructive arteriopathy, scheduled for surgery. The patients have been divided into 2 equal groups for age, sex, pathology and intensity of pain. In the first group (TTDS), at first session, a buprenorphine patch 35 microg/h (Transtec TDS) has been applied, and after 24h, a peridural catheter with elastomeric system was positioned; 100 mL (2 mg/mL) of naropine and 2 mg of morphine, 4 mL/h in 24 h, were administered. In the second group (naropine morphine, NM), buprenorphine patch was not applied and analgesia was obtained only by using peridural catheter with elastomeric system at the same doses administered in the first group. At the daily control patients with visual analogical scale (VAS)=or>40 mm received an additional dose of morphine from 2 mg to 6+/-2 mg. VAS (0-100 mm) and the evaluation of the number of the hours of sleep were used to evaluate the analgesic effectiveness of the treatment. Side effects, opioid tolerance and abuse were always recorded. All parameters were evaluated daily for a period of 20+/-5 days. The results indicate that in group TTDS there was an improvement of pain symptomatology, also confirmed by the increased hours of sleep and the lower incidence of side effects. Instead in group NM, pain control was less effective, 18 patients needed a rescue dose of morphine, and the incidence of side effects increased.