Nasal inhalation of butorphanol in combination with ketamine quickly elevates the mechanical pain threshold in the model of chronic constriction injury to the sciatic nerve of rat.
BACKGROUND
The aim of the present study is to explore the impact of butorphanol in combination with ketamine via nasal inhalation (NI) on neuropathic pain induced by chronic constriction injury (CCI) to the sciatic nerve in a rat model.


METHODS
CCI rats (n = 12) were equally randomized to four groups based on the treatments received as follows: 100 μL of 0.9% normal saline via NI (NS/NI group); 100 μg of butorphanol plus 1 mg of ketamine via NI (B + K/NI group); 100 μg of butorphanol alone via NI (B/NI group); and 100 μg of butorphanol plus 1 mg of ketamine via subcutaneous injection (B + K/SC group). Mechanical pain threshold was measured at 10 min, 30 min, 2 h, 4 h, and 6 h after drug administration.


RESULTS
The mechanical pain threshold in the B + K/NI group was improved significantly 4 h after drug administration as compared with that in the B/NI or B + K/SC group (P < 0.05). The onset and intensity of drug action in the B + K/NI group were better than those of the other two groups, but the duration of drug action was not prolonged.


CONCLUSIONS
NI of butorphanol in combination with ketamine quickly elevates the mechanical pain threshold in a rat neuropathic pain model induced by CCI to the sciatic nerve.
Department of Anesthesiology, Changhai Hospital, Shanghai, China.
Feng
F
Chen
LiQin
L
Wang
ShuJun
S
Chen
ZhiGao
Z
Li
ZhouLin
Z
Chen
XinHua
X
Zhou
Dong
D
Zhai
D000280:Administration, Inhalation; D000701:Analgesics, Opioid / Q000008:administration & dosage*; D000818:Animals; D002077:Butorphanol / Q000008:administration & dosage*; D007649:Ketamine / Q000008:administration & dosage*; D008297:Male; D009437:Neuralgia / Q000188:drug therapy*; D017288:Pain Threshold / Q000187:drug effects*; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors*; D012584:Sciatic Nerve / Q000293:injuries*
D000701:Analgesics, Opioid; D016194:Receptors, N-Methyl-D-Aspartate; D007649:Ketamine; D002077:Butorphanol
Butorphanol; Ketamine; Pain; Rat