Articles: hyperalgesia.
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Experimental neurology · Jan 2004
Cyclooxygenase inhibition in nerve-injury- and TNF-induced hyperalgesia in the rat.
After nerve injury, cyclooxygenase-2 (COX-2) is upregulated in spinal cord and peripheral nerve, the latter being dependent on tumor necrosis factor-alpha (TNF). Here we asked whether COX inhibitors attenuate pain behavior induced by chronic constrictive sciatic nerve injury (CCI) or intraneural injection of TNF (2.5 pg/ml). Rats received either 0.9% saline, the nonselective COX inhibitor ibuprofen (40 mg/kg) or the selective COX-2 inhibitor celecoxib (10 or 30 mg/kg) twice daily by gavage started 2 days before, 12 h or 7 days after surgery. ⋯ In spinal cord, no change in PGE2 levels was observed. In contrast to the marked inhibition of nerve-injury-induced upregulation of PGE2 by COX inhibitors, the effect on pain behavior was modest. Nerve-injury- and TNF-induced pain-related behavior seem to be only partly dependent on peripheral prostaglandins.
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J Pain Palliat Care Pharmacother · Jan 2004
ReviewOpioid insights:opioid-induced hyperalgesia and opioid rotation.
Opioid analgesics are an irreplaceable component of pharmacotherapy of numerous pain-producing conditions. Clinicians and patients must contend with the imperfect nature of this class of drugs, trying to balance benefits and burdens on a continual basis. New literature related to evidence-based selection of opioids and the neurobiological phenomenon of opioid induced hyperalgesia are reviewed. A matrix describing critical elements in the selection of opioid analgesics, both for initial therapy and for opioid rotation, is presented.
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Arzneimittel Forsch · Jan 2004
Randomized Controlled Trial Clinical TrialAnalgesic effects of low-dose intravenous orphenadrine in the state of capsaicin hyperalgesia. A randomised, placebo-controlled, double-blind cross-over study using laser somatosensory evoked potentials obtained from capsaicin-irritated skin in healthy volunteers.
The present investigation aimed to elucidate the analgesic efficacy of 30 mg of intravenous orphenadrine citrate (CAS 4682-36-4) in a human pain model. Eighteen healthy female and male subjects were enrolled and received single infusions of 30 mg orphenadrine citrate and matching placebo in two periods which were separated by a 1 week washout period. The study was designed as a randomised, double-blind, placebo-controlled, two-period, cross-over trial. ⋯ The effect on the central component was highly significant and more pronounced than the peripheral effect of the drug. The analgesic effect developed fast, was already present during infusion, was ongoing, and exceeded the observational period of 4 h after start of infusion. In summary, orphenadrine citrate was able to exert an analgesic/anti-hyperalgesic effect in a low-dose paradigm (30 mg dose) which was predominantly due to central/spinal mechanisms in this capsaicin model with laser somatosensory evoked potentials.
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Cutaneous allodynia, pain resulting from application of a non-noxious stimulus to normal skin, is a recently described symptom of migraine, with a potential role in directing optimal treatment for migraine attacks. Manifestations of cutaneous allodynia include discomfort when combing the hair, shaving, and wearing glasses, contact lenses, earrings or tight clothing. The exact mechanism by which a migraine attack is triggered is not known, but it has been theorised that, in some patients, once the attack has begun, central neurons can propagate information about the pain process without the need for further external stimuli. ⋯ The serotonin 5-HT(1B/1D) agonist anti-migraine agents (the 'triptans') block meningeal nociceptor transmission at presynaptic sites in the dorsal horn. Studies have shown that triptan therapy can abort pain prior to the development of central sensitisation, but not after allodynia has been established. Therefore, in the subset of patients who report symptoms of cutaneous allodynia with migraine attacks, early initiation of triptan therapy is currently the best intervention to achieve rapid, complete and sustained pain relief.
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Anesthesia and analgesia · Jan 2004
Randomized Controlled Trial Clinical TrialThe sunburn pain model: the stability of primary and secondary hyperalgesia over 10 hours in a crossover setting.
It was our aim to study the within-day stability and between-day repeatability of ultraviolet B (UVB) light-induced primary and secondary hyperalgesia over 10 h. Twenty hours after UVB irradiation of a skin spot (r = 2.5 cm) on the upper leg of 8 healthy volunteers the areas of secondary hyperalgesia to pinprick and pain tolerance thresholds to heat (HPTT) and electrical stimuli (5 and 250 Hz, electrical pain tolerance thresholds [EPTT]) were assessed. Measurements were repeated for 10 h at 2-h intervals and in 2 different sessions. Large areas of secondary hyperalgesia to pin prick were observed (5995 mm(2); SD, 1645). Primary hyperalgesia was evidenced by significant decreases of HPTT (mean difference, 6.5 degrees C; 95% confidence interval, 6.1-6.8; P < 0.001) and EPTT at 250 Hz (mean difference, 0.45 mA; 95% confidence interval, 0.13-0.78; P < 0.05) compared to normal skin. There was no trend within one session of either primary (P = 0.14 for HPTT) or secondary hyperalgesia (P = 0.95) and no difference between the two sessions (primary hyperalgesia, P = 0.28; secondary hyperalgesia, P = 0.07). The sunburn pain model provides a long time course of stable hyperalgesia with a high within-day stability and between-day repeatability for primary and secondary hyperalgesia. ⋯ The sunburn pain model provides a long time course of stable hyperalgesia with a high within-day stability and between-day repeatability for primary and secondary hyperalgesia.