Reversal of xylazine sedation in dogs

Pharmacological Treatments for Methamphetamine Use Disorder: Current Status and Future Targets

The illicit use of the psychostimulant methamphetamine (METH) is a major concern, with overdose deaths increasing substantially since the mid-2010s. One challenge to treating METH use disorder (MUD), as with other psychostimulant use disorders, is that there are no available pharmacotherapies that can reduce cravings and help individuals achieve abstinence. The purpose of the current review is to discuss the molecular targets that have been tested in assays measuring the physiological, the cognitive, and the reinforcing effects of METH in both animals and humans. Several drugs show promise as potential pharmacotherapies for MUD when tested in animals, but fail to produce long-term changes in METH use in dependent individuals (eg, modafinil, antipsychotic medications, baclofen). However, these drugs, plus medications like atomoxetine and varenicline, may be better served as treatments to ameliorate the psychotomimetic effects of METH or to reverse METH-induced cognitive deficits. Preclinical studies show that vesicular monoamine transporter 2 inhibitors, metabotropic glutamate receptor ligands, and trace amine-associated receptor agonists are efficacious in attenuating the reinforcing effects of METH; however, clinical studies are needed to determine if these drugs effectively treat MUD. In addition to screening these compounds in individuals with MUD, potential future directions include increased emphasis on sex differences in preclinical studies and utilization of pharmacogenetic approaches to determine if genetic variances are predictive of treatment outcomes. These future directions can help lead to better interventions for treating MUD.

Evaluation of the use of intranasal atipamezole to reverse the sedative effects of xylazine in dogs

OBJECTIVE

To assess the ability of intranasal atipamezole to reverse sedative effects of xylazine in dogs.

DESIGN

Prospective proof-of-concept study.

SETTING

University research laboratory.

ANIMAL

Six healthy, staff-owned dogs.

INTERVENTIONS

Dogs were sedated with 1.1 mg/kg of xylazine intravenously. The sedation score of each dog was recorded every 5 minutes until they achieved a sedation score of >13/21 for 3 readings. Once achieved, 0.3 mg/kg of atipamezole was administered intranasally using a mucosal atomization device. Sedation scores continued to be recorded every 5 minutes until successful reversal was achieved (<4/21).

MEASUREMENTS AND MAIN RESULTS

Average times to standing and normal wakefulness after administration of intranasal atipamezole were 6 minutes, 30 seconds and 7 minutes, 20 seconds, respectively.

CONCLUSIONS

Intranasal atipamezole successfully reversed the sedation effects of xylazine. The findings of this study provide justification for future controlled prospective studies into the potential use of intranasal atipamezole in a variety of settings including exposure to xylazine in operational canines as well as bioavailability studies for optimal dosing.

Refinement of the dose of doxapram to counteract the sedative effects of acepromazine in dogs

OBJECTIVES

To evaluate the effectiveness of two doses of doxapram in reversing acepromazine sedation in dogs.

METHODS

Using a crossover design, 10 adult mixed-breed dogs received 0·05 mg/kg acepromazine, intramuscularly (im) followed 30 minutes later by one of the three randomly determined treatments: 0·0625 mL/kg saline, intravenously (iv), 1·25 mg/kg doxapram, iv or 2·5 mg/kg doxapram, iv. Sedation scores were obtained by a single, blinded observer at 0, 15 and 30 minutes after acepromazine administration and at 5, 15 and 30 minutes after the treatment administration.

RESULTS

The mean baseline sedation score of all the treatments was not different among treatments. All the dogs had a significant increase in sedation score at 30 minutes after acepromazine administration. Both the low and high doses of doxapram showed a significant decrease in sedation score compared to saline, but there was no significant difference between the two doses. Five dogs in the high dose group panted after treatment injection, and this was significantly more than in the low dose group.

CLINICAL SIGNIFICANCE

Doxapram is effective in reducing the sedative effects of acepromazine over a short period of time. A dose of 1·25 mg/kg effectively decreases acepromazine sedation without causing panting.

Sedative and cardiorespiratory effects of three doses of romifidine in comparison with medetomidine in five cats

This study was designed to compare the effects of three doses of romifidine (200, 400 and 600 microg/kg) with medetomidine (80 microg/kg) administered intramuscularly to five cats. The quality of sedation and the cardiovascular and respiratory effects of each treatment were evaluated, and the onset and duration of the sedation, and the cats' recovery times, were measured. Cardiorespiratory variables were also analysed. The dose of 200 microg/kg romifidine was clinically superior to the other doses of romifidine, providing moderate sedation, with minor cardiorespiratory and other adverse effects. However none of the doses of romifidine induced as deep and reliable sedation as the dose of medetomidine.

Reversal of sedative and clinicophysiological effects of epidural xylazine and detomidine with atipamezole and yohimbine in buffaloes (Bubalus bubalis)

The sedative and clinicophysiological effects of either xylazine (0.1 mg/kg) or detomidine (50 micrograms/kg) administered epidurally to groups of five buffaloes were reversed by the intravenous administration of either yohimbine (0.125 mg/kg) or atipamezole (10 micrograms/kg). Epidural xylazine or detomidine produced bradycardia, respiratory depression, ruminal stasis and hypothermia and these effects were completely reversed within five to 15 minutes after the intravenous administration of atipamezole or yohimbine, with no signs of excitement or resedation. Atipamezole reversed the effects of xylazine or detomidine more rapidly than yohimbine.

Effect of romifidine and romifidine-butorphanol for sedation in dogs

The sedative and physiological effects of intravenous romifidine at 120 micrograms/kg were compared with intravenous romifidine (120 micrograms/kg) followed immediately by intravenous butorphanol (0.1 mg/kg) in 18 clinically normal adult beagles in a blinded randomised change-over study. Following the injection of romifidine alone the dogs became recumbent and there was an increase in a subjective score awarded to the degree of sedation. Heart rate and respiratory rate decreased and minor bradyarrhythmias were noted. The romifidine-butorphanol combination produced a significant decrease in the time to the onset of sedation and increase in the sedative effect and duration of action compared with romifidine alone. With the exception of a further decrease in heart rate and respiratory rate, there were no additional side effects following the use of the romifidine-butorphanol combination. The marked sedative effect associated with this combination would appear to be useful in the clinical situation where an increased degree of sedation is required.

Sedative effects of romifidine in the dog

The sedative and physiological effects of intravenous romifidine at 0, 20, 40, 80 and 120 micrograms/kg were investigated in five clinically normal adult male beagle dogs in a blind study using a Latin square design. Following the injection of romifidine, the dogs became ataxic and stood with a wide-based stance, they exhibited signs of skeletal muscle relaxation and their heads were lowered. All the dogs became recumbent and there was a reduction in the heart and respiratory rates. Increasing the dose from 20 to 40 micrograms/kg, or higher, produced a significant reduction in heart rate. There was am increase in the sedation score following even low doses of romifidine, and although measures of sedation showed no differences among romifidine doses, subjectively, the higher doses produced a more consistent effect. Dogs given lower doses of romifidine regained a standing position more rapidly than following the higher doses, although this effect was not significantly different. A second blind study compared the sedative effects of intravenous romifidine, at 40 and 80 micrograms/kg, with medetomidine at 10 micrograms/kg in six adult beagles. The cardiopulmonary and sedative effects were not significantly different between all regimens, although medetomidine at 10 micrograms/kg appeared to be intermediate in effect between romifidine at 40 and 80 micrograms/kg. The sedative and physiological effects of romifidine in dogs appear to be similar to other alpha2-adrenoceptor agonists. Intravenous administration provided sedation which might be clinically useful.

Reversal of xylazine-induced sedation in dairy calves with atipamezole: a field trial

Dairy calves immobilized with xylazine (XYL) were given atipamezole-HCl (ATI) at different XYL:ATI dose ratios (w/w) for reversal and the antagonistic effect of xylazine was evaluated. Control animals received saline for comparison. Intramuscular administration of xylazine (0.139-0.357 mg/kg) induced sedation with complete immobilization in all animals (n = 195) and there were no spontaneous recoveries before injection of atipamezole or saline. Atipamezole was given 10-81 min and saline 25 min after xylazine administration. Intramuscular administration of atipamezole at XYL:ATI dose ratios of 5:2 (n = 11), 10:3 (n = 21), 4:1 (n = 21) and 5:1 (n = 25) effectively antagonized the xylazine-induced immobilization and sedation. The mean times (standard deviation) from injection of atipamezole until the animals were standing for these dose ratio groups were 6.09 (3.12), 5.15 (2.87), 6.35 (2.54) and 7.86 (3.11) min, respectively. The mean time to standing for control animals (n = 11) was 94.1 (3.0) min. Intravenous administration of atipamezole at XYL:ATI dose ratios of 10:3 (n = 7), 4:1 (n = 33), 5:1 (n = 16), 8:1 (n = 27) and 10:1 (n = 9) rapidly reversed the xylazine-induced immobilization and sedation. The mean times (standard deviation) from injection of atipamezole until the animals were standing for these dose ratio groups were 0.98 (0.22), 1.32 (0.48), 1.09 (0.34), 1.39 (0.52) and 1.60 (0.69) min, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Xylazine-induced sedation in axis deer (Axis axis) and its reversal by atipamezole

Eight free-ranging axis deer (Axis axis) were captured in drive nets and injected with xylazine (3.4 +/- 0.1 mg/kg; mean +/- SEM) intramuscularly using a hand-held syringe. Xylazine induced complete immobilization and sedation in three animals, heavy sedation in three, and moderate sedation in two. The mean induction time was 10.4 +/- 1.0 min. The mean rectal temperature, heart and respiratory rates of immobilized animals were 39.2 +/- 0.4 degrees C, 75.5 +/- 6.5 beats/min and 62.1 +/- 4.2 breaths/min, respectively. All the animals were given atipamezole intravenously for reversal. The mean time from injection of xylazine to administration of atipamezole was 37.8 +/- 4.6 min. A dose ratio (w/w) for xylazine:atipamezole-HCl of 10:1 was used. The mean time from injection of atipamezole to mobility was 2.41 +/- 0.58 min. Atipamezole given intravenously effectively antagonized xylazine-induced sedation in axis deer. Only one animal showed signs of overalertness after reversal and no cases of resedation were observed.