The journal of pain : official journal of the American Pain Society
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Randomized Controlled Trial Multicenter Study Clinical Trial
Relief of painful diabetic peripheral neuropathy with pregabalin: a randomized, placebo-controlled trial.
This was a 6-week, randomized, double-blind, multicenter study evaluating the efficacy of pregabalin in the treatment of painful diabetic neuropathy. Two hundred forty-six men and women with painful diabetic neuropathy received pregabalin (150 or 600 mg/day by mouth) or placebo. The primary efficacy variable was mean pain score at the end of treatment. Efficacy results indicate that pregabalin 600 mg/day significantly decreased mean pain score to 4.3 (vs 5.6 for placebo, P = .0002) and increased the proportion of patients who had a > or =50% decrease from baseline pain (39% vs 15% for placebo, P = .002). Pregabalin also significantly reduced sleep interference, past week and present pain intensity, sensory and affective pain scores, and bodily pain and decreased by > or =50% the number of patients describing their pain as gnawing, sickening, fearful, and punishing-cruel. More patients receiving pregabalin 600 mg/day than placebo showed improvement, as rated on the Clinical and Patient Global Impression of Change scales, 73% vs 45% and 85% vs 47%, respectively. Pregabalin 150 mg/day was essentially no different from placebo. Dizziness was the most common side effect. These study results show pregabalin 600 mg/day to be safe and effective in reducing the pain and other associated symptoms of painful diabetic neuropathy. ⋯ Painful diabetic peripheral neuropathy is a challenging neuropathic pain syndrome. This randomized controlled trial demonstrates that pregabalin, a new drug that interacts with the alpha2-delta protein subunit of the voltage-gated calcium channel, is an efficacious and safe treatment for the pain of this condition.
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Review Guideline
Guidelines for the cold pressor task as an experimental pain stimulus for use with children.
The cold pressor task (CPT) involves placing a hand or forearm in cold water, a stimulus that produces a slowly mounting pain of mild to moderate intensity and is terminated by voluntary withdrawal of the limb. The CPT has been used in many studies of pain, autonomic reactivity, and hormonal stress responses. Use of the CPT with children was first reported in 1937, and it has been used since then in at least 24 published studies including more than 1700 children without reported adverse effects. However, differences in water temperature, apparatus, and procedure might contribute to conflicting results. We offer suggested guidelines for the safe construction and operation of apparatus for the CPT and for consistent administration of the task and measurement. In particular, use of continuously circulating water at a temperature of 10 degrees C +/- 1 degrees C is recommended for the CPT with children and adolescents. Data on children's pain tolerance found in CPT studies in the authors' laboratories are provided. ⋯ Differences in methodology might have contributed to conflicting results in published research using the CPT with children. These guidelines for apparatus and for administration of the CPT might be helpful to researchers planning such studies. Questions for research leading toward further methodologic refinement are identified.
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Editorial Practice Guideline Guideline
APS position statement on the use of placebos in pain management.
In the spring of 2003, the board of directors of the American Pain Society asked the APS Ethics Committee to formulate a position statement for the Society concerning the use of placebos in clinical practice (cf, reference ). A subset of the Ethics Committee under my direction composed such a statement based on the available scientific and ethical literature. We then sought feedback from the entire ethics committee as well as numerous prominent voices in the literature and presented the statement to the membership for discussion at the 2004 annual APS meeting in Vancouver, British Columbia, at both a symposium and an ethics special interest group meeting. The resultant document was approved by the APS Board and is published here for widespread distribution to the membership.
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Two experiments assessed how interpersonal transactions influence responses to cold pressor pain in women versus men. In Experiment 1, 91 young adults (57 women, 34 men) were randomly assigned to either a no transaction (NT) condition in which they coped alone with the cold pressor test or a transaction opportunity (TO) condition in which they also had the option of interacting with an empathetic, reflecting experimenter. Compared to men, women had lower pain tolerance and reported more pain and catastrophizing, although there were no gender differences in support seeking or other ways of coping. Within the TO condition, women were no more likely than men to initiate a transaction, but female speakers were more pain-focused than male speakers, and speaking with the empathetic interaction partner had generally negative effects on pain perception and coping. In Experiment 2, 126 young adults (76 women, 50 men) were randomly assigned to NT, TO, or experimenter-directed (1) Distraction (DT), (2) Reinterpretation (RT), or (3) Encouragement (ET) conditions. Although men had similar levels of pain tolerance across the 5 transaction conditions, women in NT and TO conditions exhibited reduced tolerance compared with those in the DT, RT, and ET conditions. Pain tolerance times among women in DT, RT, and ET conditions were equal to or exceeded those of men in these conditions. Together, findings suggest the nature of interpersonal transactions exerts a greater influence on women's responses to noxious stimulation than those of men. ⋯ This study adds to literature indicating that women exhibit reduced tolerance for experimentally induced pain compared with men. These results suggest that the nature of interpersonal transactions also affects women's responses to noxious stimulation, more than those of men.
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Previous studies suggest that sex differences in morphine antinociception in rodents might be attributed to the activational effects of gonadal hormones. The present study determined whether hormonal modulation of opioid antinociception in adult rats extends to opioids other than the prototypic mu agonist morphine. Male and female rats were sham-gonadectomized (sham-GDX) or gonadectomized (GDX) and replaced with no hormone, estradiol (E2, females), progesterone (P4, females), E2+P4 (females), or testosterone (males). Approximately 28 days later, nociception was evaluated on the 50 degrees C hot plate and warm water tail withdrawal tests before and after subcutaneous administration of hydromorphone, buprenorphine, U50,488, or SNC 80. In sham-GDX (gonadally intact) rats, the mu agonists and U50,488 were less effective in females than in males in at least one nociceptive test, and the delta agonist SNC 80 was less effective in males than in females. In males, gonadectomy tended to decrease, and testosterone tended to increase antinociception produced by 3 of the 4 agonists. In females, gonadectomy and hormone treatment had more variable effects, although E2 tended to decrease mu opioid antinociception. The present results suggest that activational effects of gonadal hormones are relatively modest and somewhat inconsistent on antinociception produced by various opioid agonists in the adult rat. ⋯ This study demonstrates that reproductive hormones such as testosterone in males and estradiol in females do not consistently modulate sensitivity to the analgesic effects of opioids in the adult organism.