Pain
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Paclitaxel is an effective antineoplastic drug treatment used as an anti-tumoral therapy. Unfortunately its use is associated with unwanted side effects, which include the development of peripheral neuropathies and neuropathic pain, greatly affecting the quality of life of patients. It is well known that agonists of the cannabinoid receptor are able to reduce hyperalgesia and allodynia that develop after nerve injury. ⋯ This effect was antagonized by SR 141716A, suggesting the involvement of the CB1 receptor, although the participation of CB2 receptors cannot be excluded from this study. When WIN 55,212-2 was administered intraplantar, no differences were observed between the injected paw and the contralateral paw, suggesting that systemic mechanisms are needed to reach effectiveness. From these results we suggest that cannabinoids may be an interesting alternative to reduce neuropathic symptoms induced by paclitaxel, however more work is required to assess this possibility.
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Intrathecal drug administration using implanted catheter and pump systems has been used in routine clinical practice for more than 20 years to treat chronic refractory pain or spasticity. Complications associated with the use of these systems include drug related adverse events as well as technical problems, most of which are related either to the catheter or the procedure. ⋯ We present a case of asymptomatic intraspinal migration of an intrathecal catheter three years after an uneventful implantation. To the best of our knowledge, this complication has never been reported before.
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Randomized Controlled Trial Comparative Study
Different profiles of buprenorphine-induced analgesia and antihyperalgesia in a human pain model.
Different mechanisms were proposed for opioid-induced analgesia and antihyperalgesia, which might result in different pharmacodynamics. To address this issue, the time course of analgesic and antihyperalgesic effects of intravenous (i.v.) and sublingual (s.l.) buprenorphine was assessed in an experimental human pain model. Fifteen volunteers were enrolled in this randomized, double-blind, and placebo controlled cross-over study. ⋯ The half-life of buprenorphine-induced analgesic and antihyperalgesic effects were 171 and 288 min, respectively. In contrast to pure mu-receptor agonists, buprenorphine exerts a lasting antihyperalgesic effect in our model. It will be of major clinical interest whether this difference will translate into improved treatment of pain states dominated by central sensitization.
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Randomized Controlled Trial Comparative Study
Iontophoretic administration of S(+)-ketamine in patients with intractable central pain: a placebo-controlled trial.
The efficacy of 50 and 75 mg S(+)-ketamine administered daily by an iontophoresis-assisted transdermal drug delivery system was tested against placebo in a randomized, double-blind design in 33 patients with central neuropathic pain. At baseline and 1 week after the start of treatment subjects were evaluated with standard measures of efficacy: pain intensity measured by visual analog scale (VAS), health status (Pain Disability Index and EQ-5D) and quality of life (SF-36). Safety assessment included incidence and intensity of adverse events. ⋯ Iontophoretic administration of S(+)-ketamine was well tolerated with a low incidence of adverse events (mild and transient in nature, resolving spontaneously). Iontophoretic administration of S(+)-ketamine was not more effective than placebo treatment in reducing pain scores in patients with severe central neuropathic pain. However, iontophoretic administration of 75 mg S(+)-ketamine improved the health status and the quality of life in these patients.
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Evidence has been accumulated suggesting that a dysfunction in pain inhibitory systems, i.e. in 'diffuse noxious inhibitory controls' (DNIC)-like mechanisms, might be-amongst other factors-responsible for the development of anatomically generalized chronic pain like fibromyalgia. The aim of the present study was to look for similar impairments in chronic tension-type headache (CTTH) as a regionally specific pain syndrome. Twenty-nine CTTH patients and 25 age- and sex-matched healthy control subjects participated in the study. ⋯ This group difference was present during the 'pain' as well as the 'heat' condition. Furthermore, the electrical detection and pain thresholds were affected in this group-specific manner both at the forearm and at the temple. These findings suggest that patients with CTTH suffer from deficient DNIC-like pain inhibitory mechanisms in a similar manner, as do patients with anatomically generalized chronic pain like fibromyalgia.