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Query: UMLS:C0344307 (analgesia)
 28,200 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sedative effects of medetomidine, a potent selective and specific alpha 2-adrenoceptor agonist, were evaluated in pigs using 5 different doses (30, 50, 80, 100 and 150 micrograms/kg of body weight) and compared with those of xylazine (2 mg/kg). Atropine (25 micrograms/kg) was mixed with both drugs to prevent severe bradycardia. All drugs were administered intramuscularly. Medetomidine at a dosage of 30 micrograms/kg produced more potent sedation than xylazine. The depth of sedation induced by medetomidine was dose dependent within the range from 30 to 80 micrograms/kg. At 100 or 150 micrograms/kg, the depth of sedation was mostly the similar level to that at 80 micrograms/kg but the duration was prolonged. The degree of muscle relaxation produced by medetomidine also seemed to be dose dependent from 30 to 80 micrograms/kg and was stronger than that produced by xylazine. An increase in the duration of muscle relaxation was dose dependent up to 150 micrograms/kg. No analgesic effect was produced by xylazine, however moderate analgesia was obtained by medetomidine. There were no marked changes in heart rate and respiratory rate during the observation period in pigs of any groups, however mild hypothermia after the administration of both drugs was observed. From these results, medetomidine has a significant and dose-dependent sedative effects which are much more potent than that of xylazine, and a combination of 80 micrograms/kg of medetomidine and 25 micrograms/kg of atropine is suitable for sedation with lateral recumbency and moderate muscle relaxation without notable side effects in pigs.
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PMID:Sedative effects of medetomidine in pigs. 139 Nov 73

Different dose regimens of medetomidine (a potent alpha 2-adrenergic agonist), adding up to a combined dose of 80 micrograms/kg, were administered to laboratory beagles to determine physiologic responses including neurologic. The study was intended to determine EEG responses where sufficient sedative and analgesic effects are reached with medetomidine and in contrast its effects when used with ketamine or halothane. Cardiopulmonary responses were very similar in each dose regimen, showing the characteristic properties of single doses of 80 micrograms/kg of medetomidine. Effective sedative and analgesic duration seemed to be a function of when the largest dose was administered. Adequate additional sedative and analgesic could be gained from injections at doses of half of the initial one. The potent sedative and analgesic effects of medetomidine confirmed by neurologic evaluation supports its potential use as a premedication to general anesthesia in dogs. In this study, 2 different doses of medetomidine were also tested as premedication to both ketamine HCI and halothane anesthesia. Neorologic responses were determined at the same time cardiopulmonary parameters, anesthetic quality, and dose requirements were recorded. Medetomidine was found to have favorable qualities in conjunction with these anesthetics. Cardiopulmonary parameters remained satisfactory in both groups as preanesthetic medication prior to halothane, but no additional benefits could be seen from doses of 40 micrograms/kg medetomidine compared to 20 micrograms/kg, except a significant 30% reduction in halothane requirement. The positive chronotropic and inotropic properties of ketamine restored the medetomidine-induced bradycardia and produced a short anesthetic period of 15 to 30 min depending on the dose of medetomidine. The quality of anesthesia was better when 40 micrograms/kg medetomidine was used, but recovery was quicker with 20 micrograms/kg medetomidine. Medetomidine significantly reduced cerebral activity as demonstrated by recordings of total amplitude and frequency evaluation of the EEG with compressed spectral analysis. This analytical method was effective in confirming clinical signs of sedation, analgesia, and anesthesia in canine subjects.
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PMID:Comparison of neurologic responses to the use of medetomidine as a sole agent or preanesthetic in laboratory beagles. 159 60

Medetomidine, a new alpha 2-adrenoceptor agonist produced dose-dependent (30-100 micrograms/kg i.p.) analgesia in the formalin test in rats, and this effect was reversed by atipamezole (1 mg/kg), a new alpha 2-adrenoceptor antagonist. However, medetomidine at the dose of 100 micrograms/kg did not influence tail flick latencies or latencies of the biting response to mechanical pinch stimuli. Moreover, medetomidine produced sedation and a decrease in locomotor activity. In comparison, the non-sedative monoaminergic agent, cocaine (25 mg/kg), produced highly significant analgesic effects in the formalin and mechanical pain tests. The cocaine effect in the formalin test was not reversed by atipamezole (1 mg/kg). It is concluded that the analgesic effect of medetomidine in the formalin test is due to supraspinal mechanisms related to sedation and is mediated by alpha 2-adrenoceptors. The alpha 2-adrenoceptors are not involved in cocaine-induced anagesia.
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PMID:The effect of medetomidine, an alpha 2-adrenoceptor agonist, in various pain tests. 197 6

The sedative and analgesic effects of medetomidine were studied in 18 laboratory beagles in a randomized cross-over study which was carried out in a double-blind fashion. Xylazine was included as a positive control and placebo as a negative control. Medetomidine was used at doses of 10, 30, 90 and 180 micrograms/kg i.m. compared to a dose of 2.2 mg/kg xylazine i.m. Parameters closely related to sedation were used to measure the degree of sedation. These were a posture variable (including evaluation of the dog's posture without external disturbance and resistance when laid recumbent) and a relaxation variable (including relaxation of the jaws, upper eyelids and anal sphincter). The first signs of sedation were recorded 1.5-3.5 min after administration of both drugs. The dogs sat down at 0.6-2.6 min post-injection and became prone at 1.9-5.9 min. Medetomidine dose-dependently affected the posture of the dogs and the relaxation variable--the higher the dose, the stronger and longer lasting the effect recorded. The sedative effect of xylazine was comparable to a medetomidine dose of 30 micrograms/kg. The analgesic effect was assessed as changes in the response to superficial pain induced by electrical stimuli. The response threshold increased significantly with both drugs and the effect of medetomidine was dose-dependent. The effects of the doses of 30 micrograms/kg medetomidine and 2.2 mg/kg xylazine did not differ significantly. In summary, medetomidine possessed an excellent sedative effect associated with analgesia in dogs.
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PMID:Sedative and analgesic effects of medetomidine in dogs. 256 98

The medetomidine/ketamine combination was evaluated as an anaesthetic in cats undergoing ovariectomy. It was compared with acepromazine/ketamine, xylazine/ketamine and zolazepam/tiletamine combinations. 60 animals, divided into 6 groups of 10 animals were involved. Medetomidine highly potentiated the anaesthetic effects of ketamine and balanced the two main disadvantages of this drug: weak muscle relaxation and poor analgesia in deep organs. 80 micrograms medetomidine/kg--5 mg ketamine/kg provided a duration of anaesthesia longer than 1 mg acepromazine/kg--10 mg ketamine/kg, and not significantly different from those induced by 1 mg xylazine/kg--10 mg ketamine/kg or 7.5 mg zolazepam/kg--7.5 mg tiletamine/kg. Furthermore, it produced a better muscle relaxation than acepromazine/ketamine and zolazepam/tiletamine combinations. The analgesia in deep organs observed after medetomidine/ketamine administration appeared to be more substantial than that observed after acepromazine/ketamine or xylazine/ketamine combinations. The stimulating effect on heart rate of ketamine compensated the bradycardiac effect of medetomidine. Nevertheless, the administration of 80 micrograms medetomidine/kg--5 mg ketamine/kg resulted as with xylazine/ketamine, in decreasing heart rate whereas acepromazine/ketamine and zolazepam/tiletamine combinations did not exhibit bradycardiac effect. It was concluded that the medetomidine/ketamine combination provided a suitable anaesthesia for cats characterized by rapid induction, good muscle relaxation, good analgesia and bradycardia.
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PMID:Medetomidine/ketamine anaesthesia in cats. 257 Dec 60

Studies on the clinical efficacy of medetomidine, a novel alpha-2 adrenoceptor agonist, are reviewed. Medetomidine has been shown to produce a reliable state of sedation, relaxation and recumbency suitable for small animal practice. In dogs, the optimal clinical dose for examinations, clinical procedures and minor surgical interventions seems to be 30-40 micrograms/kg intramusculary and in cats 80-110 micrograms/kg. Other effects of medetomidine reported include bradycardia, nausea and vomiting. Occasional muscle jerkings have been also reported after medetomidine injection. In special investigations, medetomidine has successfully been used in wound suturation and ovariohysterectomy in dogs and for sedation in dogs with heart diseases. Medetomidine-ketamine combination has been shown to be useful for anesthesia and immobilization in cats and zoo animals. The medetomidine-fentanyl combination was tested in dog: The administration of fentanyl increased the sedation and analgesia obtained with medetomidine. Medetomidine appears to be a potent sedative and analgesic agent for clinical use.
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PMID:The clinical efficacy of medetomidine. 257 Dec 66

Experiments with 3 doses of medetomidine (20, 40 and 80 micrograms/kg, iv. and im., respectively) were carried out on 90 dogs of 16 breeds in the Small Animal Surgery of the University of Veterinary Science, Budapest. Changes in hematology as well as in AST, AP, BUN, creatinine were studied. Medetomidine administered iv deepened the sedation and lengthened tranquillization dose-dependently. After im administration the sedative effect was still dose-dependent, but the duration of its clinical effectiveness could not be lengthened significantly. The development of the sedation could however, be quickened. The iv administration increased the level of analgesia in proportion to dosage; the im application could change the level of pain-killing effect of the drug, but could not lengthen it. According to the laboratorical determinations, regardless of the dosage and the route of application, medetomidine did not affect the AST and AP enzyme activities, or the BUN and creatinine values.
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PMID:Clinical investigations of medetomidine in dogs. 257 Dec 68

The suitability of medetomidine in suturation of wounds of extremities was evaluated. Two doses, 80 micrograms/kg and 40 micrograms/kg, were used. Lidocaine was used only in those cases when the procedure could not be performed without a local anaesthetic. In the group 80 micrograms/kg (22 dogs) the wounds could be sutured in 77% of cases without lidocaine. When the dosage was 40 micrograms/kg (22 dogs), treatment was successful in 55% of cases respectively. It is concluded that medetomidine should be administered at a dosage level of 80 micrograms/kg for analgesia when suturing wounds of the legs of dogs. If the analgesia is not sufficient it can be completed with local infiltration of lidocaine. Medetomidine in combination with lidocaine seems to be very useful for analgesia in minor surgical procedures.
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PMID:Suturation of wounds of extremities in dogs using medetomidine as sedative and analgesic drug. 257 Dec 70

The analgesic effect of medetomidine was studied in ten laboratory beagles. The doses of medetomidine used were 10, 30 and 80 micrograms/kg BW. Xylazine (3 mg/kg BW) was included as a positive control and placebo as a negative control. The test utilized two independently randomized Latin square designs (5 x 5) and was carried out in a double blind fashion. Noxious stimuli were induced with a round pointed thermal probe which was set to produce a temperature of +44.9 +/- 0.2 degrees C. The wall of the external auditory canal was touched with the heated point of the probe. The time period from the start of the attachment to the avoidance reflex was measured and recorded as response time. To avoid tissue damage the heat treatment was stopped after 5 s even though the dog did not respond. Medetomidine clearly prolonged the response time. At the highest dose of medetomidine (80 micrograms/kg) all dogs reached the analgesic stage where they did not respond to the heat treatment. At 30 micrograms/kg of medetomidine half of the dogs had a prolonged response time. The lower dose of 10 micrograms/kg had no appreciable effect. Xylazine-induced analgesia was comparable to that of 30 micrograms/kg of medetomidine: half of the dogs lost their avoidance reflex. In conclusion, medetomidine proved to have a dose dependent analgesic effect in experimental auricular pain in dogs.
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PMID:Effects of medetomidine on the experimental auricular pain in dogs. 257 Dec 72

Medetomidine, (+/-)-4-[1-(2,3-dimethylphenyl)ethyl]-1H-imidazole, is a very potent, selective and specific full agonist at both pre- and postsynaptic alpha 2-adrenoceptors as demonstrated in several models both in vitro and in vivo. In receptor binding experiments the alpha 2/alpha 1 selectivity ratio of medetomidine is 1620 compared to 260, 220 and 160 for detomidine, clonidine and xylazine, respectively. The alpha 2-adrenoceptor activity of medetomidine resides predominantly in its d-enantiomer (dexmedetomidine). Medetomidine induces a dose-dependent decrease in the release and turnover of noradrenaline, dopamine and serotonin in the CNS as measured by changes in metabolite concentrations or using pharmacological intervention techniques. Inhibition of sympathetic tone in the CNS by medetomidine leads for a characteristic pattern of pharmacodynamic responses including e.g. hypotension, bradycardia, sedation, relief of anxiety, analgesia and hypothermia. The potent, dose-dependent sedative effects of medetomidine have been demonstrated in several classical animal models (e.g. decrease in spontaneous motility in rats and mice, potentiation of barbiturate-induced anaesthesia in rats and mice, induction of sleep in young chicks). At high doses medetomidine has hypnotic of anaesthetic effects, a property which distinguishes it clearly from detomidine, clonidine and other alpha 2-agonists. The pharmacological, neurochemical and behavioral effects of medetomidine can be inhibited by prior, simultaneous of subsequent administration of a selective and specific alpha 2-antagonist, atipamezole. Besides verifying that the main pharmacodynamic effects of medetomidine are alpha 2-mediated, this finding forms a strong basis for the use of atipamezole as a reversing agent against medetomidine-induced effects in veterinary practice.
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PMID:Pharmacological profiles of medetomidine and its antagonist, atipamezole. 257 Dec 75


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