title: Analgesic effect and pharmacological mechanism of fentanyl and butorphanol in a rat model of incisional pain.
abstract: OBJECTIVE
  To explore analgesic effects of fentanyl and butorphanol on incisional pain in rats and to investigate the pharmacological mechanism of combination.
  
  
  METHODS
  Seventy rats were randomly divided into control group (group N, n = 10), fentanyl group (group F, n = 30), and butorphanol group (group B, n = 30), to determine median effective dose (ED50) in fentanyl and butorphanol. Another 50 rats were treated with both fentanyl and butorphanol (joint group) to quantitatively detect response rate of joint application. Ninety rats were randomly divided into 1/4 ED50 fentanyl (group 1, n = 30), 1/2 ED50 fentanyl (group 2, n = 30), and 3/4 ED50 fentanyl (group 3, n = 30), to detect the correlation between combined pharmacological effects of 2 drugs and their dose proportionality. Statistical analysis was performed using SPSS 17.0.
  
  
  RESULTS
  Probit analysis revealed that ED50 of fentanyl was 4.1 μg/kg, whereas ED50 of butorphanol was 295 μg/kg. The qualitative response rate of combination (Po) was 0.84, and expected qualitative response rate (Pe) was 0.75, with no statistical significance (P = 0.3). Furthermore, probit analysis showed that 155 μg/kg butorphanol with 1/4 ED50 fentanyl could reach experimental ED50 of combination of 2 drugs; 115 μg/kg butorphanol with 1/2 ED50 fentanyl could reach experimental combination ED50; and 88 μg/kg butorphanol with 3/4 ED50 fentanyl could reach experimental combination ED50.
  
  
  CONCLUSIONS
  Both fentanyl and butorphanol showed good analgesic effect on incisional pain in rats, but fentanyl was superior to butorphanol. The pharmacological mechanism of combination with ED50 of fentanyl and butorphanol showed independent joint action, and the combination efficacy was related to the dosage.
authors.affiliation: Department of Anesthesiology, the First Affiliated Hospital of Liaoning Medical University, Jinzhou 121001, PR China.
authors.forename: Quan
authors.initials: Q
authors.lastname: Chen
authors.affiliation: Department of Anesthesiology, the First Affiliated Hospital of Liaoning Medical University, Jinzhou 121001, PR China.
authors.forename: You
authors.initials: Y
authors.lastname: Shang
authors.affiliation: Department of Anesthesiology, the First Affiliated Hospital of Liaoning Medical University, Jinzhou 121001, PR China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Department of Anesthesiology, the First Affiliated Hospital of Liaoning Medical University, Jinzhou 121001, PR China.
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.affiliation: Department of Oncology, the First Affiliated Hospital of Liaoning Medical University, Jinzhou 121001, PR China. Electronic address: liping826_222@126.com.
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.affiliation: Department of Anesthesiology, the First Affiliated Hospital of Liaoning Medical University, Jinzhou 121001, PR China. Electronic address: liuguoli_lgl@126.com.
authors.forename: Guo-Li
authors.initials: GL
authors.lastname: Liu
mesh_terms: D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000627:therapeutic use*; D000818:Animals; D002077:Butorphanol / Q000008:administration & dosage / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D004359:Drug Therapy, Combination; D005283:Fentanyl / Q000008:administration & dosage / Q000627:therapeutic use*; D005528:Foot / Q000601:surgery; D007431:Intraoperative Complications / Q000188:drug therapy*; D008297:Male; D010146:Pain / Q000188:drug therapy*; D010147:Pain Measurement / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000701:Analgesics, Opioid; D002077:Butorphanol; D005283:Fentanyl
keywords: Butorphanol; Fentanyl; Median effective dose; Pharmacological effect; Rat model; Response rate