Tiletamine/zolazepam and dexmedetomidine with tramadol provide effective general anesthesia in rats

Background:Tiletamine/zolazepam is a dissociative anesthetic combination commonly used in small animals but information is limited in rats.The alpha-2 agonist,dexmedetomidine,has gained popularity in laboratory animal anesthesia.Tramadol is a weak opioid mu agonist.The aim of this study was to assess whether the tiletamine/zolazepam/dexmedetomidine(ZD)combination effectively provides a surgical anesthesia plane comparable to tiletamine/zolazepam/dexmedetomidine with tramadol(ZDT)in a minor procedure in rats.Methods:Rats were induced with ZD or ZDT.After the loss of paw withdrawal,a small incision was made on the rats’left thighs as a surgical stimulus.Rats were maintained under a surgical anesthesia plane by assessing the loss of the paw withdrawal reflex for 45 minutes,then atipamezole was administered.Monitored anesthesia parameters included:(a)physiological parameters-pulse rate(PR),respiratory rate(RR),tissue oxygen saturation(%SpO 2),and body temperature;(b)duration parameters-induction time,onset and duration of surgical anesthesia plane,onset of recovery,and recovery time.Results:PR was significantly lower at 10 minutes in ZD and 5 minutes in ZDT groups.No difference was observed for RR,%SpO 2,and body temperature.Likewise,there were no differences for duration parameters:induction time was less than 3 minutes;onset and duration of surgical anesthesia plane were approximately 5 and 45 minutes,respectively;onset of recovery(time to move)was 51 minutes;and recovery time was 52 minutes,respectively.Conclusion:These data suggest the ZD combination provides a surgical anesthesia plane comparable to ZDT in a rat incisional pain model.

Lipid bound extended release buprenorphine(high and low doses)and sustained release buprenorphine effectively attenuate post-operative hypersensitivity in an incisional pain model in mice(Mus musculus)

Background:Extended-release buprenorphine(XR)is indicated for pain management in rodents,but little is known about its use in mice.This study aimed to investigate whether high dose XR effectively attenuates post-operative hypersensitivity better than low dose XR in a mouse model of incisional pain.Methods:Mice(n 44)were randomly assigned to 1 of 4 treatment groups:(a)saline(1 ml/kg SC,once);(b)sustained release buprenorphine(Bup-SR,1 mg/kg SC,once);(c)low dose extended-release buprenorphine(XR-lo,3.25 mg/kg SC,once);(d)high dose extended-release buprenorphine(XR-hi,6.5 mg/kg SC,once).On days1,0(4 hours),1,2,and 3,mechanical and thermal hypersensitivities were evaluated,and plasma buprenorphine concentrations were measured.Results:Mechanical(days 0-2)and thermal(days 0-1)hypersensitivities were ob-served in the saline group.Bup-SR,XR-lo,and XR-hi attenuated mechanical hyper-sensitivity on days 0,1,and 2.None of the treatment groups,except XR-Lo on day 0,attenuated thermal hypersensitivity on days 0 or 1.Plasma buprenorphine concen-tration peaked at 4 hours(day 0)in all treatment groups and remained greater than 1 ng/mL on days 0-2.No abnormal clinical observations or gross pathologic findings were seen in any groups.Conclusion:The results indicate XR-hi did not effectively attenuate post-operative hypersensitivity better than XR-lo.Thus both 3.25 and 6.5 mg/kg XR are recom-mended for attenuating post-operative hypersensitivity for at least up to 48 hours in mice.