• Journal of Veterinary Clinics
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• v.20 no.3
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• pp.286-293
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• 2003

The cardiopulmonary and antagonistic effects of atipamezole, to medetomidine (30 ug/kg, IM)-tiletamine/zolazepam (10 mg/kg, IV) were determined. Twelve healthy mongrel dogs ,(4.00$\pm$0.53 kg, mean$\pm$SD) were randomly assigned to the four experimental groups (control, A30; atipamezole 30 ug/kg, A60; atipamezole 60 ug/kg, A150; atipamezole 150 ug/kg) with 3 dogs in each group. Atropine (0.03 mg/kg, IM), medetomidine, and tiletamine/zolazepam (TZ) were injected 10 minute intervals. Atipamezole was injected intravenously 15 minutes after TZ injection. Mean arousal time (MAT) was 52.50$\pm$4.98, 43.06$\pm$2.60, 32.83$\pm$8.13, and 14.36$\pm$1.60 minutes in control, A30, A60, and Al50 groups respectively. In Al50 group, MAT was significantly reduced (P < 0.05). but mean walking time (MWT) was similar to that in control group. In recovery period, the higher doses of atimapezole, the rougher recovery including head rocking, hypersalivation, and muscle twitching. Five of twelve dogs vomited within 5 minutes after medetomidine injection. In Control group, heart rate significantly decreased in all recording stages except 15 minutes after TZ injection, 10 minutes after medetomidine injection in all groups, and 40 minutes after atipamezole injection in A30 group (P < 0.05). In Al50 group, atipamezole reversed the respiratory depression induced by medetomidine. Arterial blood pressure was significantly decreased 10minutes after medetomidine injection and 15 minutes after TZ injection in almost dogs in this study (P < 0.05). From 10 minutes after atipamezole injection to arousal time, arterial blood pressure was progressively increased in A60 and A150 group. Any value of blood gas analysis and CBC, and serum chemistry values were not significantly changed except pH of Al50 at 10 minutes after medetomidine injection. As shown in present study, atipamezole(150 ug/kg) is considered to exert a useful reversal effect in dogs anesthetized with medetomidine-tiletamine/zolazepam combination.

• YAKHAK HOEJI
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• v.55 no.2
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• pp.98-105
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• 2011

To search the minimum structural requirement of tricyclic isoxazole analogues (1~30) as new class potent antidepressant, thee-dimensional quanti- tative-structure relationship (3D-QSAR) models between substituents ($R_1{\sim}R_5$) of tricyclic isoxazoles and their antidepressant activity against medetomidine-induced loss of righting were performed and discussed quantitatively using comparative molecular field analysis (CoMFA) and comparative molecular similarity indies analysis (CoMSIA) methods. The correlativity and predictability ($r^2$=0.484 and $q^2$=0.947) of CoMSIA-2 model were higher than those of the rest models. The inhibitory activity against medetomidine-induced loss of righting was dependent on electrostatic field (43.4%), hydrophobic field (35.3%), and steric field (21.2%) of tricyclic isoxazoles. From the CoMSIA-2 contour maps, it is predicted that the antidepressant activity of potent antidepressants against medetomidine-induced loss of righting will be able to increase by the substituents ($R_1{\sim}R_5$) which were in accord with CoMSIA field.

• Journal of Veterinary Clinics
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• v.10 no.1
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• pp.37-46
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• 1993

This study was carried out to evaluate the effects of yohimbine on medetomidine sedation. Twenty dogs were sedated with medetomidine(0.04mg/kg, IM). Twen쇼 minutes after the injection, ten dogs were injected with saline(0.1mg/, IV)for the control group and the others were injected wi yohimbine(0.1mg/kg, IV)for the experimental group. Onset, recovery time, respiratory rate, body temperature, blood chemistry, electrocardiogram(ECG) finding were recorded. The results obtained were summarized as follows; 1. Onset of the sedation was fast and favorable. 2. Recovery time was shorted significantly by yohimbine treatment(p<0.01). 3. Respiratory rates were decreased significantly, but increased to normal level after the yohimblne treatment(p<0.01). 4. Heart rates were decreased significantly; but increased to normal level after the yohimbine treatment(p<0.01). 5. Body temperatures of dogs in the experimental group revealed higher level than those of control group(p<0.01). 6. Arrythmias were observed in both groups but relieved to normal after the yohimbine treatment. 7. Blood chemistry values were not changed significantly by medetomidine and yohimbine treatment. 8. These results showed that yohimbine is an excellent antagonist of medetomidine.

• Journal of Veterinary Clinics
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• v.22 no.3
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• pp.194-197
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• 2005

This study was performed to investigate the anesthetic effects of intramuscularly administered medetomidinetiletamine/zolazepam ($Zoletil^{(R)}$) in the green iguana. The doses of medetomidine were 50, 100 and 150 ${\mu}g/kg$ in each groups and tiletamine/zolazepam was administered at doses of 10 mg/kg in all groups. Heart rate, respiratory rate and body temperature were measured. Anesthetic depth was evaluated by righting reflex. In all study groups, heart rate and respiratory rate significantly decreased at 5 minutes after anesthetic administration, and gradually increased after 30 minutes. The present study suggested that the combination of 100 ${\mu}g/kg$ of medetomidine and 10 mg/kg of tiletamine/zolazepam provided rapid, safe, and effective anesthesia for the green iguana.

• Journal of Veterinary Clinics
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• v.23 no.1
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• pp.18-21
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• 2006

This study was performed to investigate the reverse effects of atipamezole in green iguana anesthetized with intramuscular administration of medetomidine-tiletamine/zolazepam ($Zoletil^{\circledR}$). Heart rate, respiratory rate and body temperature were measured. Anesthetic depth was evaluated by righting reflex. In all study groups, heart rate and respiratory rate significantly decreased at 5 min after anesthetic administration, and gradually increased after atipamezole administration. The present study suggested that $500{\mu}g/kg$ atipamezole was effective reversal dosage for $500{\mu}g/kg$ medetomidine and 10 mg/kg liletamine/zolazepam combination anesthesia in green iguanas.

• Journal of Veterinary Clinics
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• v.30 no.6
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• pp.421-427
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• 2013

There are many intramuscularly injectable drugs commonly used for anesthesia in dogs and combination of drugs were used for decrease the side effects. The objective of this study was to evaluate the anesthetic and cardiopulmonary effects of butorphanol-tiletamine-zolazepam-medetomidine and tramadol-tiletamine-zolazepam-medetomidine in dogs. Ten healthy beagle dogs (intact male; mean body weight : $9.5{\pm}1.60$ kg) were used in the study. Experimental animals were divided into two groups (n=5, each) and received 0.2 mg/kg of butorphanol (BZM) and 2 mg/kg of tramadol (TZM) according to the group after injection of $Zoletil^{(R)}$ (5 mg/kg) and medetomidine (10 ug/kg). All drugs were administered intramuscularly. Anesthesia and recovery, sedation and analgesia score, cardiovascular and respiratory parameters were measured. Induction and recovery time were not significantly different between the groups. Anesthesia time was $117.4{\pm}25.64$ minute and $81.2{\pm}12.50$ minute in BZM and TZM groups, respectively. Sedation and analgesia were satisfied in both groups. In both groups, common side effects related to the medetomidine, significant bradycardia and hypertension were not observed. There were no significant changes in respiratory data. In conclusion, tiletamine-zolazepam-medetomidine in combination with either butorphanol or tramadol can be suitable anesthetic protocol for minor procedures in dogs. They produced adequate anesthesia characterized by rapid induction, adequate analgesia and muscle relaxation without remarkable side effects.

• Journal of Veterinary Clinics
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• v.27 no.6
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• pp.674-678
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• 2010

The effects of medetomidine on the degree of analgesia and sedation in rats were evaluated. The rats were randomly divided into six groups: saline, 1 mL/kg (group 'Saline'); butorphanol, 2.0 mg/kg; medetomidine, 0.2, 0.4, 0.8 or 1.6 mg/kg (group 'MED0.2', 'MED0.4', 'MED0.8' and 'MED1.6', respectively). The degree of analgesia was measured in the $50^{\circ}C$ hot-water tail-flick latency test, and the degree of sedation was evaluated using the numerical sedation score (NSS) and the righting reflex. All doses of medetomidine, except MED0.2, significantly increased the analgesic effect compared to the Saline group. Variables in the MED0.4 and MED0.8 groups, but not in the MED1.6 group, were significantly increased compared to those in the MED0.2 group. However, analgesia with all doses of medetomidine was not significantly different compared to that with butorphanol. Saline and butorphanol treatments did not induce sedation and loss of righting reflex during the recording period. NSS in the MED0.4, MED0.8 and MED1.6 groups were significantly higher than that in the MED0.2 group. NSS in the MED0.8 and MED1.6 groups were not significantly different from that in the MED0.4 group. The latency to loss of righting reflex in the MED0.8 and MED1.6 groups decreased significantly compared to that in the MED0.2 group. Thus, 0.4 and 0.8 mg/kg of medetomidine provided not only reliable analgesia but also sedation to rats. In conclusion, 0.4 to 0.8 mg/kg medetomidine could be a useful chemical restraint method in rats.

• Journal of Veterinary Clinics
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• v.29 no.3
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• pp.220-225
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• 2012

This study examined the anesthetic and cardiopulmonary effects of xylazine or medetomidine in combination with ketamine-butorphanol in dogs. Five dogs were used in both the medetomidine-ketamine-butorphanol (MKB) group and the xylazine-ketamine-butorphanol (XKB) group. The procedures for the two groups were performed 4 weeks apart. MKB group showed a shorter duration for anesthesia than XKB group. Other factors were not statistically significant between the two groups. The MKB group showed signs of bradycardia, therefore cautious patient monitoring is necesessary. The XKB showed a longer anesthetic time and less adverse effects, however the MKB combination was more expensive and had less advantages. In conclusion, the results suggested the recommended use of both MKB and XKB in procedures that need approximately 50 minutes. If patients have a risk of bradycardia, one should be cautious of using a medetomidine-xylazine-butorphanol combination. Both MKB and XKB did not have much adverse effects; however MKB did not have advantages when compared to XKB. Therefore, XKB may be more effective when compared to MKB.

• Korean Journal of Veterinary Research
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• v.37 no.2
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• pp.331-338
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• 1997

최근 동물의 진통 및 진정을 목적으로 널리 사용되고 있는 imidazole 유도체인 clonidine, medetomidine, etomidate 등의 약물과 xylazine의 효과를 발정정지기의 척출 돼지 자궁근에서 검토하였다. Clonidine($10^{-8}{\sim}10^{-6}M$)이나 medetomidine($10^{-8}{\sim}10^{-6}M$)은 xylazine과 비슷한 정도로 용량의존적인 자궁근의 수축을 일으켰다. Clonidine, medetomidine, xylazine 등의 $EC_{50}$는 각각 24.7nM, 19.9nM, 45.1nM이었다. 그러나 etomidate는 $10^{-6}M$ 미만의 농도에서 반응이 거의 없었으며, $10^{-6}M$ 이상에서 수축반응을 일으켰다. 이들 agonists의 효과는 yohimbine($10^{-8}{\sim}10^{-6}M$), idazoxan($10^{-7}{\sim}10^{-5}M$), tolazoline($10^{-7}{\sim}10^{-5}M$) 등의 ${\alpha}_2-adrenoceptor$ antagonists에 의해서 차단되었으나, ${\alpha}_1-adrenoceptor$ antagonist인 prazosin ($10^{-6}M$)에 의해서는 차단되지 않았다. 또한 $Ca^{2+}-free$ medium이나 verapamil($10^{-5}M$)의 전처치에 의해서 이들 agonist의 효과가 완전히 차단되었다. 결론적으로 발정정지기의 돼지 자궁근에서 clonidine, medetomidine, etomidate, xylazine 등은 ${\alpha}_2-adrenoceptors$의 흥분을 통해 자궁근의 수축을 일으키며, 이 효과는 voltage-dependent $Ca^{2+}$ channels을 통한 extracellular $Ca^{2+}$ influx의 증가에 의한 것으로 추론하였다.

• Journal of Veterinary Clinics
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• v.28 no.2
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• pp.211-218
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• 2011

The aims of this study were to investigate the anesthetic effects of medetomidine-midazolam-ketamine (MMK) combination and to compare antagonistic effects of atipamezole and yohimbine in dogs anesthetized with MMK. Eighteen adult male healthy beagles were used in this study. All dogs were anesthetized with intramuscular (IM) administration of medetomidine (0.04 mg/kg), midazolam (0.2 mg/kg) and ketamine (5 mg/kg) in one syringe. Intravenous (IV) administration of atipamezole (0.24 mg/kg, MMKA), yohimbine (0.2 mg/kg, MMKY) or saline solution (0.1 ml/kg, MMK) was administered 20 minutes after MMK combination anesthesia. Induction and recovery times, scores of sedation and analgesia, heart rate, blood pressure, rectal temperature, respiratory rate and blood gases were determined and recorded for each dog. Mean anesthesia times, sternal recumbency times, standing times and walking times in the MMKA and MMKY groups were significantly shorter than those in the MMK group. But there were not significantly different between MMKA and MMKY groups. In all groups, MMK administration produced a satisfactory sedation and analgesia for all dogs. However, after administration of atipamezole or yohimbine the scores for posture and response to noxious stimuli were significantly lower in the MMKA or MMKY group than those in the MMK group. MMK produced good sedation and anesthesia effects, and atipamezole or yohimbine can be used as a safe and effective agent for antagonizing the MMK anesthesia in dogs.