Pain
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Methadone is a synthetic opiate receptor agonist that has been available for more than 40 years. Although its main use has been in the maintenance treatment of opioid addicts, it has excellent analgesic effects and low cost. ⋯ Methadone should be titrated carefully and individualized doses and intervals should be determined for each patient. Future research should attempt to determine the equi-analgesic dose for chronic use, its effectiveness and tolerance when used in high doses, and its absorption and tolerance using alternative routes, e.g., rectal and subcutaneous.
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Variability of physiological parameters was used as a measure of stress in the newborn infant. There was a significant increase in variability of the heart rate (P < 0.01) when the stab of the heel prick occurred in addition to the other elements of the procedure (positioning, warming, alcohol swab cleansing and squeezing). This dummy procedure itself caused some increase in variability although this was not significant at the 5% level. There were similar significant increases in variability of the respiratory rate and O2 and CO2 tensions in the blood (P < 0.05) during the stab procedure.
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Clinical Trial Controlled Clinical Trial
Enhancement of morphine analgesia by fenfluramine in subjects receiving tailored opioid infusions.
We evaluated the ability of fenfluramine, a serotonin releaser, to increase the analgesic potency of morphine administered by tailored i.v. infusion. Ten normal volunteers participated in 4 test sessions, involving different treatments on different days: (1) oral placebo/saline infusion, (2) oral placebo/morphine infusion, (3) oral fenfluramine (60 mg)/saline infusion, and (4) oral fenfluramine/morphine infusion. Subjects experienced repetitive painful dental electrical stimuli at strong but tolerable intensities during testing. ⋯ Fenfluramine significantly increased the analgesic potency of morphine during the opioid infusion, while fenfluramine alone produced borderline analgesic effects. Fenfluramine alone decreased alertness slightly, but did not significantly increase morphine side effects. Thus, we conclude that fenfluramine enhances the analgesic potency of morphine without a parallel increase in opioid side-effect potency.
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Comparative Study
Are mechanical and cold allodynia in mononeuropathic and arthritic rats relieved by systemic treatment with calcitonin or guanethidine?
The putative antinociceptive action of guanethidine and calcitonin systemically injected has been compared in 2 rat models of persistent experimental pain: Freund's adjuvant-induced arthritis (n = 29) and mononeuropathy induced by 4 loose ligatures around the sciatic nerve (n = 24). Guanethidine (30 mg/kg, i.v.) and calcitonin (0.125 mg, s.c.) were injected once a day over 1 week, when hyperalgesia was fully developed. ⋯ Guanethidine treatment was ineffective on hyperalgesia exhibited in arthritic rats but was able to reduce reliably and even suppress the abnormal reactions to cold stimulus in neuropathic animals. The lack of hypoalgesic action of calcitonin versus its beneficial action in bone repair, as well as the possible role(s) of the sympathetic system in neuropathic versus arthritic pain and in hyperalgesia versus physical signs of inflammation, are discussed.
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Randomized Controlled Trial Clinical Trial
Quantitative sensory examination during epidural anaesthesia and analgesia in man: effects of morphine.
In a double-blind placebo-controlled cross-over study the effects of epidural morphine (4 mg) on somatosensory functions were investigated in 10 healthy volunteers. Detection, pain detection and pain tolerance thresholds to thermal, mechanical and electrical stimuli as well as magnitude rating of short-lasting stimuli of the same modalities were monitored before and for 10 h after epidural administration of 4 mg of morphine or saline. Epidural morphine induced a naloxone-reversible (0.1 mg/kg, i.v.) increase in pain detection threshold to heat and mechanical stimuli and in pain tolerance threshold to heat, mechanical and electrical stimuli. ⋯ Segmental distribution of pruritus was reported by 7 subjects following epidural morphine which was replaced by a short-lasting burning sensation following naloxone administration. Naloxone (0.1 mg/kg) preceeded by placebo did not change somatosensory functions. These results indicate that the somatosensory effect of epidural morphine is dependent on the types of afferent fibres activated as well as on the duration and intensity of the stimulus.