Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0030193 (pain)
 261,466 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Intrathecal administration of alpha adrenoceptor agonists in rats produces a significant elevation of nociceptive thresholds as measured by hot-plate and tail-flick latencies. That these antinociceptive effects were antagonized by alpha adrenoceptor antagonists suggests that spinal adrenoceptors modulate the rostrad transmission of nociceptive information. The role of spinal adrenoceptors in the modulation of nociception in visceral pain tests has in the past been examined primarily in the writhing model of visceral pain. Recently, however, a new model of visceral pain has been developed which utilizes colorectal distension (CRD) as the noxious visceral stimulus in awake, unanesthetized animals. CRD produces a pressor response and contraction of the abdominal and hindlimb musculature (a visceromotor response), both of which are readily quantifiable. Inhibition of both of these pseudoaffective reflexes is indicative of antinociception. The effects of intrathecally administered adrenoceptor agonists on the responses to CRD were examined in conscious rats. The visceromotor and pressor responses to CRD were dose-dependently inhibited by the alpha-2 adrenoceptor agonists clonidine and ST-91 and the nonselective alpha adrenoceptor agonist norepinephrine (NE), but not by the alpha-1 adrenoceptor agonist methoxamine or the alpha adrenoceptor agonist isoproterenol. Tizanidine, an alpha-2 adrenoceptor agonist, dose-dependently inhibited the pressor response to CRD but failed to significantly elevate the visceromotor threshold in response to CRD. The effects produced by clonidine, NE and ST-91 were antagonized by pretreatment with yohimbine. The effects produced by tizanidine were antagonized by idazoxan.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Antinociceptive effects of intrathecal adrenoceptor agonists in a rat model of visceral nociception. 197 Oct 18

Experiments were performed in rats to determine if the alpha 2-adrenergic agonist tizanidine has an antinociceptive effect when injected intrathecally, and whether the analgesia is accompanied by changes in blood pressure. Rats were chronically implanted with catheters in the lumbar subarachnoid space. Antinociception was evaluated in conscious rats with the tail-flick test. Increasing tizanidine doses produced increases in analgesic efficacy, with 25 micrograms producing a significant long-lasting antinociception. This tail-flick analgesia was very similar to that produced by clonidine (25 micrograms) and morphine (8 micrograms) in peak effect and duration. Doses as high as 250 micrograms produced only a transient hind limb motor dysfunction in 43% of the animals. Daily injections of 25 micrograms tizanidine over 5 days produced a decrease in antinociception, with the peak effect at day 5 at 59% of that at day 1. Blood pressure, in rats lightly anesthetized with halothane, was not affected by tizanidine injections up to 250 micrograms. Tizanidine appears to be a promising non-opiate analgesic for intrathecal usage.
Pain 1990 Mar
PMID:Effect of intrathecal tizanidine on antinociception and blood pressure in the rat. 232 97

Tizanidine [5-chloro-4-(2-imidazolin-2-yl-amino)-2,1,3-benzothiadiazole] is able to increase the pain threshold in the tail-flick test in mice. The effect of tizanidine was investigated after treatment of mice with drugs influencing central monoaminergic and GABAergic mechanisms. A drug that inhibits the synthesis and storage of monoamines and drugs that cause specific lesions of monoaminergic neurons had no consistent effect on the antinociceptive action of tizanidine. The action of tizanidine was antagonized by the alpha 2-adrenoreceptor antagonist, yohimbine, but not by the alpha 1 antagonist prazosin, nor by dopamine, serotonin and GABA receptor antagonists. These results indicate that the antinociceptive action induced by tizanidine may be mediated by alpha 2-adrenoreceptors.
 ...
PMID:Antinociceptive activity induced by tizanidine and alpha 2-adrenoreceptors. 282 57

The antinociceptive actions of morphine and tizanidine (an alpha 2-adrenergic agonist) administered intrathecally in a rat model of mononeuropathic pain were investigated. Tizanidine increased to normal levels the intensity of a noxious pressure stimulus required to induce paw withdrawal (p < 0.01) and decreased the duration of limb withdrawal from both normal-temperature and cooled floors in a dose-dependent manner (p < 0.01). Tizanidine had virtually no effect on the latency of paw withdrawal from a noxious heat stimulus. In comparison, morphine significantly decreased, in a dose-dependent manner, limb withdrawal from the normal-temperature and cooled floors and increased to cutoff values the withdrawal latencies of both noxious heat and pressure stimuli (p < 0.01). The effect of tizanidine was limited to the hyperalgesic limb and served to normalize reactive latencies, whereas morphine affected both hindlimbs and increased latencies to supranormal cutoff values. These data suggest that intrathecal tizanidine may be more specific than morphine in reversing the allodynia and hyperpathia associated with neuropathic pain states and may be of value in the management of patients with these clinical syndromes.
 ...
PMID:A comparison of intrathecally administered narcotic and nonnarcotic analgesics for experimental chronic neuropathic pain. 789 21

The effects of the intrathecal alpha 2-agonists tizanidine and clonidine and the somatostatin analog octreotide on an experimental rat model of tactile allodynia were investigated to determine the therapeutic potential for treating chronic neuropathic pain. Allodynia was induced by ligating the rat sciatic nerve. The mechanical threshold for paw withdrawal was assessed by applying von Frey hairs to quantify analgesic actions. Mean 50% paw withdrawal thresholds were converted to the percentage of maximum possible effect (%MPE) where %MPE = (postdrug threshold-predrug threshold) divided by (15 g-predrug threshold) x 100. Dose-response curves were plotted for suppression of paw withdrawal 30 minutes after intrathecal injection of various doses of tizanidine, clonidine, and octreotide. Thresholds on the non-lesioned side were greater than 15 g. The lesioned side had baseline thresholds of less than 4.5 g. Dose-response curves were established for the antiallodynia effects of each drug. Tizanidine and clonidine at a 25-micrograms dose increased the threshold to greater than 97% of the MPE, but caused transient hindpaw weakness or sedation. No side effect was observed at a 10-micrograms dose, at which the threshold was 88-96% of MPE. Intrathecal octreotide modestly increased the threshold to only 49-67% of MPE, showing a lesser analgesic effect, although no side effect was observed at a 4-micrograms dose. The antiallodynic effects of intrathecal tizanidine and clonidine were more potent than that of octreotide.
 ...
PMID:Effects of intrathecal nonnarcotic analgesics on chronic tactile allodynia in rats: alpha 2-agonists versus somatostatin analog. 904 98

An opioid withdrawal syndrome was precipitated by naloxone administration in rats treated with morphine. The withdrawal caused alteration of several physiological signs. The aim of the study was to investigate whether the altered physiological profiles were modified by utilising tizanidine, an alpha 2 adrenergic receptor agonist which is capable of affecting faecal and urinary excretion, rectal temperature, pain threshold levels and salivation. To induce an opioid withdrawal syndrome, morphine was administered in three daily intraperitoneal injections for four days at doses of 9, 16 and 25 mg/kg (1st day), 25, 25 and 50 mg/kg (2nd day), 50, 50 and 50 mg/kg (3rd day) and 50, 50 and 100 mg/kg (4th day): naloxone was injected (30 mg/kg) i.p. 180 min after the last morphine injection. Tizanidine was administered orally at 0.17, 0.35 and 0.7 mg/kg, 60 min after the last morphine injection. Signs such as faecal and urine excretion, rectal temperature and latency times to thermal stimulus, salivation, jumping and wet dog shakes were affected in different ways by morphine, naloxone, tizanidine and by the combination of these agents. Notably, the administration of tizanidine in rats receiving morphine and naloxone decreased the intensity of certain withdrawal symptoms, including altered excretion of faeces and urine, salivation and wet dog shake behavior. Body temperature levels and nociceptive threshold values were also modified. The effects caused by tizanidine administration may be due to its alpha 2 receptor agonist activity interfering with a mechanism involved in the regulation of these previously mentioned withdrawal symptoms. Thus, the use of this drug may be indicated as a possible control of the acute phase of opioid withdrawal in heroin addicts.
 ...
PMID:Effects of tizanidine administration on precipitated opioid withdrawal signs in rats. 958 75

The purpose of this research trial is to assess the effectiveness and tolerability of tizanidine in neuropathic pain. In an open-label study, patients with neuropathic pain received 1 to 4 mg of tizanidine once daily for 7 days, followed by weekly dose escalation of 2 to 8 mg to his/her effective or maximum tolerated dose or a maximum of 36 mg over an 8-week period. Treatment effects were assessed, using average weekly pain scores as well as biweekly scores for patient global assessment of pain relief, the neuropathic pain scale, and wisconsin brief pain inventory. Frequency and severity of adverse events were examined also. Twenty-three patients were enrolled. The mean average weekly pain score at baseline was 6.9, which decreased by 1.7 points at the end of week 8 to 5.2 (p < or =.01). A total of 15 patients (68%) reported that their pain relief was improved or much improved with tizanidine therapy, and 2 of these patients became completely pain-free. The following neuropathic pain qualities were significantly lower at week 8 compared with baseline: intense, sharp, hot, dull, cold, sensitive, unpleasant, and deep pain. There was a significant decline in pain quantity and interference of pain on quality of life from baseline to week 8. The mean effective or maximum tolerated dose was 23 mg/day (range 6 to 36 mg/day). Side effects consisted primarily of dizziness/lightheadedness (52%), drowsiness (48%), fatigue/weakness (43%), dry mouth (39%), gastrointestinal upset (30%), and sleep difficulty (22%). One patient developed significant elevation in liver function tests (LFTS) With symptoms at week 4. Tizanidine therapy was discontinued. LFTS returned to normal in 3 weeks. Tizanidine might be an effective treatment for neuropathic pain, offering an alternative for patients poorly responsive to other medications. A larger, randomized placebo-controlled trial is recommended. In addition, comparative studies with alternative agents should be sought.
J Pain 2000
PMID:Effectiveness of tizanidine in neuropathic pain: an open-label study. 1462 12

Tizanidine is a centrally acting alpha-2 adrenoreceptor agonist widely used in the treatment of spasticity in patients with cerebral or spinal injury, and it is causing drawsiness in some of them. Based on these drug actions, we administered tizanidine to 21 spastic quadriplegic children with severe sleep disturbance not improved by conventional therapies. All these patients were showing abnormalities of both the induction and maintenance of sleep. The dosage of tizanidine was 0.1 to 0.2 mg/kg/day, divided into two or three doses. If daytime drowsiness was severe, tizanidine admistration was restricted to just prior to bedtime. In 13 patients (61.9%), we found improvement in sleep induction and/or maintenance. Moreover, patients' families were satisfied with the treatment. There were no detectable side effects except facial pallor in two patients (9.5%) whose treatment was discontinued. Severe muscle hypertonia causes severe pain, which generates strong sympathetic nerve activity and subsequent sleep disturbance. We consider that tizanidine has direct effects on the induction of sleep, and promotes muscular relaxation bringing about good sleep. We conclude that tizanidine is useful for the treatment of refractory sleep disturbance in spastic quadriplegic patients.
 ...
PMID:[Effects of tizanidine for refractory sleep disturbance in disabled children with spastic quadriplegia]. 1556 Mar 87

Myofascial pain syndrome (MPS) is difficult to treat. The efficacy and safety of tizanidine, an alpha2-adrenergic agent with effects on spasticity and pain, in treating MPS was evaluated. Female subjects (n = 29) with MPS of 9 to > 52 weeks' duration and mean age 37.5 (range 20-51) years, who also had reduced pressure thresholds, were enrolled. Subjects were titrated up to 12 mg of tizanidine over 3 weeks and maintained for 2 weeks. Sleep was assessed via visual analog scale (VAS), pain intensity via short form McGill questionnaire including VAS, disability/level of function, and pressure threshold (tested by algometry) at baseline, weeks 3 and 5, and 1 week after tizanidine was discontinued. Patient and physician global assessments of treatment were reported at week 5. Twenty-four subjects completed the study. Pain intensity and disability decreased significantly from baseline at weeks 3 and 5 and after washout (P < .001). Pressure threshold and sleep improved for all study periods (P < .001). Tizanidine was rated as good to excellent in relieving pain by 89% of subjects and 79% of physicians. No serious adverse events occurred. Tizanidine was effective in the treatment of MPS.
Pain Physician 2002 Oct
PMID:Tizanidine is effective in the treatment of myofascial pain syndrome. 1688 22

Tizanidine and aceclofenac individually have shown efficacy in the treatment of low back pain. The efficacy and tolerability of the combination have not yet been established. The objective of the study was to evaluate the efficacy and safety of aceclofenac-tizanidine fixed dose combination against aceclofenac alone in patients with acute low back pain. This double-blind, double-dummy, randomized, comparative, multicentric, parallel group study enrolled 197 patients of either sex in the age range of 18-70 years with acute low back pain. The patients were randomized to receive either aceclofenac (100 mg)-tizanidine (2 mg) b.i.d or aceclofenac (100 mg) alone b.i.d for 7 days. The primary efficacy outcomes were pain intensity (on movement, at rest and at night; on VAS scale) and pain relief (on a 5-point verbal rating scale). The secondary efficacy outcomes measures included functional impairment (modified Schober's test and lateral body bending test) and patient's and investigator's global efficacy assessment. aceclofenac-tizanidine was significantly superior to aceclofenac for pain intensity (on movement, at rest and at night; P < 0.05) and pain relief (P = 0.00) on days 3 and 7. There was significant increase in spinal flexion in both the groups from baseline on days 3 and 7 with significant difference in favour of the combination group (P < 0.05). There were significantly more number of patients with excellent to good response for the aceclofenac-tizanidine treatment as compared to aceclofenac alone (P = 0.00). Both the treatments were well tolerated. In this study, aceclofenac-tizanidine combination was more effective than aceclofenac alone and had a favourable safety profile in the treatment of acute low back pain.
 ...
PMID:Aceclofenac-tizanidine in the treatment of acute low back pain: a double-blind, double-dummy, randomized, multicentric, comparative study against aceclofenac alone. 1942 91


1 2 Next >>