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Query: UMLS:C0030193 (pain)
 261,466 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. It has been reported previously that clonidine can potentiate tyramine-evoked mydriasis on the pain-free side of cluster headache patients. We examined whether a single oral dose of clonidine (200 micrograms) can also potentiate tyramine-evoked mydriasis in healthy subjects, using mydriasis to methoxamine, a directly acting sympathomimetic amine, as a control. 2. Eight healthy male volunteers participated in four weekly sessions. In the first two sessions (Experiment 1) the effect of clonidine or placebo on the mydriasis to tyramine hydrochloride eyedrops (75 mM; 2 x 10 microliters), and in the last two sessions (Experiment 2) the effect of clonidine or placebo on the mydriasis to methoxamine hydrochloride eyedrops (20 mM; 2 x 10 microliters) was examined. In both experiments subjects were allocated to drugs and sessions according to a double-blind balanced design. In both experiments, pupil diameter of both the treated and the untreated eyes was recorded in standard ambient light and in the dark, before, and 2 h after clonidine/placebo, via binocular infrared television pupillometry. Salivation (dental roll technique), systolic and diastolic blood pressure (sitting), heart rate, and self-ratings of mood and feelings (visual analogue scales), were also measured before, and 2 h after the ingestion of clonidine or placebo. 3. Both tyramine and methoxamine produced a significant mydriasis, which was more prominent in the light condition (change in resting pupil size; mm +/- s.e.mean: tyramine/light 1.05 +/- 0.28; tyramine/dark: 0.73 +/- 0.15; methoxamine/light: 1.65 +/- 0.28; methoxamine/dark: 0.85 +/- 0.15). Clonidine produced a significant miosis in the untreated eye which was more prominent in the light condition (change in resting pupil size; mm +/- s.e.mean: Experiment 1, light: -1.34 +/- 0.19; Experiment 1, dark: -0.46 +/- 0.1; Experiment 2, light -0.97 +/- 0.18; Experiment 2, dark: -0.29 +/- 0.17). Clonidine had no significant effect on either tyramine- or methoxamine-evoked mydriasis. 4. In agreement with previous reports, clonidine significantly reduced salivation (g, mean +/- s.e.mean; Experiment 1: -0.84 +/- 0.22; Experiment 2: -0.55 +/- 0.11), systolic blood pressure (mm Hg; Experiment 1: -17.5 +/- 3.76; Experiment 2: -23.38 +/- 4.67), diastolic blood pressure (mm Hg; Experiment 2: -12.38 +/- 2.05), alertness (mm; Experiment 2: -24.19 +/- 5.40), and anxiety (mm; Experiment 1: -13.82 +/- 4.60), indicating the presence of pharmacodynamically effective tissue levels of the drug. 5. These results show that a single oral dose (200 micrograms) of clonidine causes significant miosis in human subjects, and fails to potentiate tyramine-evoked mydriasis. This indicates that the pupil on the asymptomatic side of cluster headache patients is affected differently from the pupils of healthy volunteers by tyramine and/or clonidine.
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PMID:Comparison of the effects of clonidine on tyramine- and methoxamine-evoked mydriasis in man. 873 Sep 71

The relative roles of spinal cord stimulation and the spinal infusion of opioids in the treatment of chronic, non-cancer lower body pain remains unclear. This report contains a retrospective analysis of patients with chronic lower body, neuropathic pain and treated over a 5 year period. Unilateral leg and/or buttock pain was treated initially with spinal stimulation and bilateral leg or mainly low back pain was treated initially with spinal infusions. 26 patients received spinal stimulation. Pain relief was > or = 50% in 16 (62%) with increased activity levels. Stimulator coverage was most difficult or failed in patients with buttock pain. 16 patients received long-term spinal infusions. Pain relief was > or = 50% in 2 (13%) but 25-49% in another 8 (50%) with stable infusion doses and was best in patients requiring low-dose (< 1 mg/h morphine intrathecal) infusions in the trial period. The review indicates that spinal infusions may be best for bilateral or axial pain that has not responded to spinal stimulation. Clonidine appears to be an alternative in high-dose morphine patients. New diamond-shaped electrode and dual quadripolar arrays appear to be very helpful for back, buttock, and/or bilateral leg pain patterns.
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PMID:Spinal cord stimulation versus spinal infusion for low back and leg pain. 874 96

Sympathetic nervous system stimulation, which releases noradrenaline, influences the nociceptor activity which develops after tissue injury. The alpha 2-adrenergic agonist, clonidine, produces analgesia through a central mechanism but also inhibits noradrenaline release at terminal nerve fibre endings. Clonidine may induce analgesia when administered at peripheral sites. This study assesses the potential analgesic effect of clonidine after intra-articular administration. Forty ASA I-III patients, scheduled for arthroscopic knee surgery under general anaesthesia were allocated randomly in 4 groups of 10 patients each, at the end of the surgical procedure. In the control group (group 1), the patients received 20 ml of intra-articular isotonic saline. In group 2, the patients received 150 micrograms of clonidine diluted in 20 ml of isotonic saline injected into the knee joint. In group 3, the patients were given 20 ml of intra-articular isotonic saline and clonidine 150 micrograms was injected subcutaneously. In group 4, morphine 1 mg, diluted in 20 ml of isotonic saline, was injected into the knee joint. Postoperative pain was assessed in a double-blind fashion using a visual analogue scale (VAS) at 1, 2, 3, 6 and 24 h after the end of surgery. VAS scores were significantly lower in groups 2 and 4, compared to groups 1 and 3, at 1 and 2 h after surgery. The delay between intra-articular injection and further postoperative analgesic administration was significantly longer (P < 0.05) in group 2 (533 +/- 488 min) compared to groups 1 and 3 (70 +/- 30 min and 132 +/- 90 min, respectively). The difference was not significant between group 4 (300 +/- 419 min) and the other groups. We conclude that a low dose of intra-articular clonidine produces analgesia unrelated to vascular uptake of the drug. This study further supports a peripheral analgesic effect of clonidine.
Pain 1996 Mar
PMID:Peripheral analgesic effect of intra-articular clonidine. 878 26

Sufentanil or a sufentanil-clonidine combination was evaluated to determine whether the basal rate in patient-controlled epidural analgesia (PCEA) might affect the daily consumption, quality of analgesia or incidence of side effects. Following Caesarean section delivery, 60 patients were randomly assigned to receive one of the four following PCA regimens (15 patients per group) for the relief of post-operative pain by the epidural route: sufentanil 2 micrograms mL-1 in 0.9% NaCl, demand dose 5 micrograms i.e. 2.5 mL, (group S+ with, group S without an infusion at 2.5 mL hr-1) or sufentanil 2 micrograms mL-1 + clonidine 3 micrograms mL-1, demand dose 5 micrograms sufentanil + 7.5 micrograms clonidine i.e. 2.5 mL (group SC+ with and SC without an infusion of 2.5 ml hr-1). The other PCA settings (Bard I PCA pump) were a lock out of interval of 10 min and a 1 h limit of 20 micrograms sufentanil and 30 micrograms clonidine i.e. 10 mL. The parameters measured were the analgesic drug consumption and number of dose demands during the first 24 h, pain scores at 6 h intervals, side effects and quality of sleep. The concurrent infusion increased the dose requirements regardless of the content of the syringe. Consumption of sufentanil was the highest in those patients receiving the plain solution with a basal infusion. Clonidine addition reduced the dose requirements but only significantly in those receiving the background infusion. Patients treated with the mixture tended to reach lower pain scores than those receiving sufentanil only without basal rate. Patients receiving the mixture with basal rate requested significantly fewer additional demands compared with the three other groups, but this did not influence the quality of sleep. Since side effects were more frequently registered in the patients in this group, it was concluded that the optimum regimen was the sufentanil-clonidine combination but with deletion of the basal rate.
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PMID:Potentiation of sufentanil by clonidine in PCEA with or without basal infusion. 895 87

The effect of the addition of clonidine 2 micrograms kg-1 to prilocaine 0.5% for intravenous regional anaesthesia (IVRA) in the arm was investigated in 56 healthy patients using a randomized, double-blind study. The characteristics of the sensory and motor block, quality of analgesia, development of post-operative pain sensations and haemodynamic variables were studied in three groups (IVRA with prilocaine, IVRA with prilocaine and clonidine, IVRA with prilocaine and systemic application of clonidine at tourniquet release). There were no significant differences between the groups concerning the onset and recovery characteristics of sensory and motor blockade, post-operative pain or side effects. In those patients receiving clonidine, mean arterial pressure decreased significantly (24-28%, respectively) after tourniquet release, while heart rate remained unchanged. Clonidine as an adjunct to prilocaine seems to be of limited benefit during and after intravenous regional anaesthesia.
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PMID:The addition of clonidine to prilocaine for intravenous regional anaesthesia. 904 57

Postoperative administration of clonidine is an effective treatment for shivering. However, the ability of this drug to stop postanesthetic shivering when administered intraoperatively remains controversial. Furthermore, the relative efficacy of clonidine during isoflurane and propofol anesthesia remains unknown. We therefore evaluated the incidence of postanesthetic shivering in patients given clonidine during nitrous oxide/isoflurane or propofol anesthesia. Because clonidine is an analgesic, we also evaluated postoperative pain and analgesic requirements. We studied 60 patients undergoing elective ear or nose surgery. General anesthesia was induced with 2.0 mg/kg propofol, 1.5 micrograms/kg fentanyl, and 0.1 mg/kg vecuronium. General anesthesia was maintained with isoflurane and 70% nitrous oxide in one group of patients; in the other, a continuous infusion of propofol (8 mg.kg-1.h-1) was administered (without nitrous oxide). Five minutes before tracheal extubation, patients in each group were randomly assigned to receive saline, placebo, or 3 micrograms/kg clonidine intravenously. Postanesthetic shivering was evaluated by a blind investigator. Postoperative pain was assessed using a visual analog scale. Postoperative shivering was observed in 53% of the patients given isoflurane without clonidine and in 13% of the patients given propofol without clonidine. No patient given clonidine shivered. Clonidine administration significantly reduced postoperative pain. The incidence of postanesthetic shivering was significantly less after propofol anesthesia than after isoflurane/nitrous oxide anesthesia. However, a late intraoperative bolus administration of 3 micrograms/kg clonidine prevents postoperative shivering in patients given either type of anesthesia.
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PMID:Late intraoperative clonidine administration prevents postanesthetic shivering after total intravenous or volatile anesthesia. 905 12

The aim of this randomized, double-blind trial of postoperative thoracic epidural analgesic infusions was to determine whether clonidine at 10 microg/h (group C10, n = 22), 15 microg/h (Group C15, n = 24), or 20 microg/h (Group C20, n = 24) improved postoperative analgesia in patients undergoing abdominal gynecologic surgery, without side effects or hemodynamic changes, when added to a 5-mL/h infusion of 0.125% bupivacaine and fentanyl 2 microg/mL (Group CO, n = 22). The 24-h study infusion was supplemented, as required, by patient-controlled epidural fentanyl. Groups were similar for age, weight, duration, and type of surgery. Clonidine produced a dose-dependent improvement in analgesia at rest. Only 20 microg/h significantly increased the percentage of patients who experienced no pain with coughing (relative risk 1.44, 95% confidence interval 1.24-1.94), reduced pain scores with coughing (P < 0.05), and significantly lowered supplementary fentanyl requirements (P < 0.05). Groups were similar for sedation, pruritus, nausea, time to ambulation, and satisfaction with analgesia. Clonidine produced a dose-dependent decrease in blood pressure and pulse rate and an increase in vasopressor requirement (P < 0.01). Epidural clonidine infused at 20 microg/h improves analgesia during coughing when combined with epidural bupivacaine-fentanyl in patients undergoing lower abdominal surgery but is associated with hemodynamic changes and increased vasopressor requirement.
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PMID:Postoperative epidural infusion: a randomized, double-blind, dose-finding trial of clonidine in combination with bupivacaine and fentanyl. 917 14

The effects of pharmacological modulation of adrenergic receptors on colonic motor and sensory function are unclear. We studied 40 healthy volunteers in a single-blind design; 12 received saline, and the remaining 28 received either clonidine, yohimbine, phenylephrine, or ritodrine. A barostat-manometric assembly in the left colon recorded drug effects on fasting and postprandial motor function, compliance, and sensation in response to standardized phasic balloon distensions delivered in random order. Clonidine reduced and yohimbine increased fasting, but not postprandial tone, by 63.2 +/- 22.3% and 24.8 +/- 8.8% (SE), respectively. Clonidine tended to reduce fasting phasic activity in the descending and sigmoid colon. A power exponential model provided the best fit to the compliance curve. Clonidine significantly increased colonic compliance. Clonidine reduced and yohimbine increased colonic perception of pain but not gas sensation during distension. Phenylephrine and ritodrine did not influence colonic motor or sensory function in the present studies. Thus alpha 2-receptors modulate fasting colonic tone and compliance and alter perception of pain but not gas during mechanical stimulation of the colon.
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PMID:Adrenergic modulation of human colonic motor and sensory function. 937 95

Epidural administration of clonidine, a partial alpha 2-adrenergic agonist, provides effective relief for patients with intractable cancer pain. However, clonidine's long plasma elimination half-life suggests a potential for plasma accumulation following repeated doses or constant infusion. Adult male and female cancer patients experiencing severe, intractable pain were administered a continuous epidural infusion (30 micrograms/h) of clonidine hydrochloride for 14 days. Plasma clonidine concentrations were determined for 31 patients using a radioimmunoassay with a limit of quantitation of 0.062 ng/mL. Mean (+/- SD) plasma clonidine concentration and calculated total body clearance after 7 days of infusion (respectively, 2.19 +/- 1.17 ng/mL, n = 24; 279 +/- 184 mL/min, n = 27) were comparable to those following 14 days of infusion (2.50 +/- 1.51 ng/mL, n = 19; 272 +/- 163 mL/min, n = 21). Clonidine does not appear to accumulate in the plasma compartment during prolonged (14-day) continuous epidural infusion in cancer patients.
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PMID:Plasma concentrations and disposition of clonidine following a constant 14-day epidural infusion in cancer patients. 938 89

Opiates remain the most common form of analgesic therapy in the burn patient today. Because of increased opiate requirements, optimal relief of burn pain continues to be a problem for these patients. The purpose of this article is to summarize those alternative pain control methods that appear in the literature. For instance, in minor burns acetominophen continues to be a useful first line analgesic. Non-steroidal anti-inflammatory drugs (NSAID) and benzodiazepine are generally combined with opiates while entonox seems to be used commonly in the adolescent patients to relieve procedural pain. Antidepressants appear to enhance opiate-induced analgesia while anticonvulsants are useful in the treatment of sympathetically maintained pain following burns. Ketamine has been extensively used during burn dressing changes but its psychological side-effects have limited its use. Clonidine, however, has shown promise in reducing pain without causing pruritus or respiratory depression. Other forms such as transcutaneous electrical nerve stimulation (TENS), psychological techniques, topical and systemic local anaesthetics are also useful adjuncts.
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PMID:Adjunctive methods of pain control in burns. 942 10


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