Pain physician
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Randomized Controlled Trial
Influence of CYP2D6 activity on pre-emptive analgesia by the N-methyl-D-aspartate antagonist dextromethorphan in a randomized controlled trial of acute pain.
There is some evidence that dextromethorphan (DM) is effective as a pre-emptive analgesic agent. DM is mainly metabolized to dextrorphan (DOR) by CYP2D6 whose activity can be inhibited by pharmacologic intervention. ⋯ CYP2D6 inhibition by quinidine influenced the pre-emptive analgesic effectiveness of DM confirming that CYP2D6 phenotypic switch increases the neuromodulatory effect of oral dextromethorphan.
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Chronic non-cancer-related pain affects a large proportion of the adult population and is often difficult to manage effectively. Although opioid analgesics have been used to relieve chronic pain of different etiologies, opioids are associated with a range of side effects that may reduce patient quality of life and lead to reduced compliance with treatment.Tapentadol is a centrally acting analgesic with 2 mechanisms of action, μ-opioid receptor agonism and norepinephrine reuptake inhibition, that is available in an extended-release formulation for the management of chronic pain. ⋯ Tapentadol ER (100 - 250 mg bid) is effective for moderate to severe osteoarthritis pain, low back pain, and pain related to DPN and provides efficacy similar to that of oxycodone HCl CR (20 - 50 mg bid) for patients with osteoarthritis and low back pain. Tapentadol ER treatment has been associated with better gastrointestinal tolerability and compliance with therapy than oxycodone CR, which suggests that tapentadol ER may be a better option for the long-term management of chronic pain.
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Opioids have been the mainstay analgesics for postoperative, cancerous, and chronic noncancerous pain. Common concerns regarding the use of opioids include the development of physical dependence and addiction. However, as a potential complication of opioid therapy, opioid-induced hyperalgesia (OIH) is often overlooked. ⋯ We present 2 cases of OIH resulting from administration of tramadol, which is a synthetic analogue of codeine and exhibits 10-fold less affinity for mu-opioid receptors, in patients suffering from chronic pain. The 2 cases presented herein imply the importance of recognizing OIH in patients medicated with tramadol if analgesic effects are lost in the context of dose titration, when generalized pain is reported without any evidence of disease exacerbation. While OIH associated with ultra-low dose opiates seems to be quite rare, if it is suspected, switching to other drugs and an appropriate treatment should be considered.
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Opioids are the cornerstone therapy for the treatment of moderate to severe pain. Yet, unconfirmed evidence suggests that chronic exposure to opioids may cause hypersensitivity to pain, a phenomenon known as opioid-induced hyperalgesia (OIH). ⋯ A 4-week regimen of open-label hydromorphone therapy results in a dose-dependent OIH, which negatively correlates with its analgesic effect. Future randomized, controlled, and blinded studies are needed to verify these preliminary results.
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Excluding a vascular origin of exercise-related pain is often difficult in clinical practice. Recent papers have underlined the frequent association of concurrent lumbar spine degenerative disease and peripheral arterial disease. Furthermore, even when suspected, isolated exercise-induced proximal ischemia is difficult to diagnose. Measurement of transcutaneous oxygen pressure (tcpO2) is an interesting and accurate method to differentiate proximal (buttock) from distal (calf) regional blood flow impairment (RBFI) during exercise. ⋯ Isolated proximal-without distal RBFI is found in approximately one out of 7 patients complaining of symptom limiting claudication with a borderline or normal resting ABI. Exercise-tcpO2 may help to discriminate patients with arterial claudication that could benefit from invasive vascular investigations and procedures.