Articles: opioid.
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Development of tolerance is a well known pharmacological characteristic of opioids and a major clinical problem. In addition to the known neuronal mechanisms of opioid tolerance, activation of glia has emerged as a potentially significant new mechanism. We studied activation of microglia and astrocytes in morphine tolerance and opioid-induced hyperalgesia in rats using immunohistochemistry, flow cytometry and RNA sequencing in spinal- and supraspinal regions. ⋯ No evidence for the activation of glia in the brain was seen. Our results suggest that glial activation associated with opioid tolerance and opioid-induced hyperalgesia occurs mainly at the spinal level. The transcriptome data suggest that the microglial activation pattern after chronic morphine treatment has similarities with that of neuropathic pain.
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Randomized Controlled Trial
Influence of morphine and naloxone on pain modulation in Rheumatoid Arthritis, Chronic Fatigue Syndrome/Fibromyalgia and controls: a double blind randomized placebo-controlled cross-over study.
Impaired pain inhibitory and enhanced pain facilitatory mechanisms are repeatedly reported in patients with central sensitization pain. However, the exact effects of frequently prescribed opioids on central pain modulation are still unknown. ⋯ This study revealed anti-hyperalgesia effects of morphine in CFS/FM and RA patients. Nevertheless, these effects were comparable to placebo. Besides, neither morphine nor naloxone influenced deep tissue pain, temporal summation or CPM. Therefore, these results suggest that the opioid system is not dominant in (enhanced) bottom-up sensitization (temporal summation) or (impaired) endogenous pain inhibition (CPM) in patients with CFS/FM or RA.
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Pain control after open abdominal surgery often includes multimodal analgesia with thoracic epidural or transversus abdominis plane (TAP) block. After liposomal bupivacaine was approved for TAP blocks in 2015, it became an alternative to indwelling catheters. However, the pharmacokinetics and safety of its use during the perioperative period have not been thoroughly investigated, especially in conjunction with parenteral opioids. We present a case report of an elderly patient having urgent laparoscopic converted to open abdominal surgery, who experienced postoperative respiratory depression in the recovery room after multimodal therapy with liposomal bupivacaine TAP blocks, intravenous (IV) opioids, and ketorolac.
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Opioids are frequently used for the treatment of chronic pain, and patients taking high doses are at increased risk of complications and adverse opioid-related events. Ketamine is appealing as an opioid adjunct because of its lack of respiratory depression and potential prevention of hyperalgesia and central sensitization. We present a case in which a ketamine infusion was utilized over a 7-day period to provide rapid taper of a daily dose of 400 mg of morphine equivalents to less than one-third of that dose on discharge with unchanged pain levels and no symptoms of opioid withdrawal.