Anesthesiology
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The antidepressant amitriptyline is commonly used orally for the treatment of chronic pain, particularly neuropathic pain, which is thought to be caused by high-frequency ectopic discharge. Among its many properties, amitriptyline is a potent Na(+) channel blocker in vitro, has local anesthetic properties in vivo, and confers additional blockade at high stimulus-discharge rates (use-dependent blockade). As with other drug modifications, adding a phenylethyl group to obtain a permanently charged quaternary ammonium derivative may improve these advantageous properties. ⋯ N-phenylethyl amitriptyline appears to have a narrow therapeutic range but is much more potent than lidocaine, providing a block duration several times longer than any clinically used local anesthetic. Further work in animal models of neuropathic pain will assess the potential use of this drug.
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Ketamine is analgesic in experimental and clinical studies of inflammatory, neuropathic, and postoperative pain. Its role in the treatment of visceral pain is less known. The authors investigated the effect and site of action of ketamine on reflex responses evoked by urinary bladder distension (UBD). The effects of other clinically available N-methyl-d-aspartate (NMDA) receptor antagonists on these responses were also studied. ⋯ Ketamine inhibited, in a dose-dependent fashion, the Delta MAP and EMG responses to UBD, an effect likely caused by actions within the spinal cord. Similar inhibition observed with systemic dextromethorphan and memantine treatments suggests that the analgesic effect of ketamine is caused by antagonism of the NMDA receptor. Pretreatment with ketamine did not have a preventive effect in this model of bladder nociception.
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Randomized Controlled Trial Clinical Trial
Effect of parecoxib, a novel intravenous cyclooxygenase type-2 inhibitor, on the postoperative opioid requirement and quality of pain control.
The analgesic efficacy and side effect profile of intravenous parecoxib, a novel cyclooxygenase type-2 (COX-2) inhibitor, was assessed in a double-blinded, placebo-controlled study involving patients undergoing major gynecologic surgical procedures. ⋯ Intravenous parecoxib (20 or 40 mg) was effective in decreasing the PCA opioid requirement after lower abdominal surgical procedures. However, it failed to improve pain management or reduce opioid-related side effects in the early postoperative period.
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Postoperative nausea and vomiting (PONV) occurs frequently after gynecologic surgery. Because hemodynamic condition seems to be influential, women presenting with preoperative orthostatic dysregulation may have an increased risk for PONV. The aim of the present study was to assess the relationship between preoperative orthostatic dysregulation and the incidence of PONV. ⋯ Women presenting with orthostatic dysregulation and arterial hypotension in their history exhibit an increased risk of PONV.