title: Evaluation of the peripheral analgesic effect of sufentanil lipid nanoparticles.
abstract: OBJECTIVE
  We wished to evaluate the effect of sufentanil lipid nanoparticles on peripheral analgesia of inflammatory pain model rats.
  
  
  METHODS
  Ninety SD rats were randomly divided into an inflammatory model group (group A, n = 54) and a blank control group (group B, n = 36). Group A was further divided into the sufentanil lipid nanoparticles group (group A1, n = 18), the sufentanil group (group A2, n = 18), and the inflammatory pain model group (group A3, n = 18); group B was divided into the sufentanil lipid nanoparticles group (group B1, n = 18) and the sufentanil group (group B2, n = 18). Rats of group A were given a formalin injection in the foot to produce the inflammatory pain model. Group B rats were given a normal saline foot injection of the same dosage. Then, groups A1 and B1 were given sufentanil lipid nanoparticles (0.82 μg/kg) treatment. Groups A2 and B2 were given sufentanil of the same dosage, and group A3 were given normal saline. Pain scores of Group A rats were recorded and analyzed. The ELISA method was adopted to determine drug concentration in rat brain, plasma, and the inflammatory pain/subcutaneous area.
  
  
  RESULTS
  Pain scores of rats in group A3 were always higher than those in groups A1 and A2, and the pain scores of group A2 were higher than in group A1 0-30 min after administration (P < 0.05). The brain drug concentration in groups A2 and B1 fluctuated over time; the brain drug concentrations of groups A2 and B2 were respectively higher than those of groups A1 and B1 (P < 0.05). There was no significant difference between the plasma drug concentrations of different groups at the same time point (P > 0.05); however, there was a notable difference within each group at different time points (P < 0.05), and the drug concentration of the inflammatory tissues in group A1 changed significantly over time (P < 0.05). Thirty minutes after administration, drug concentration in the inflammatory site of group A1 was higher than that of groups A2, B1, and B2 (P < 0.05).
  
  
  CONCLUSIONS
  Sufentanil lipid nanoparticles had a comparatively weak effect on the central nervous system because of their features such as large particle size and targeted and controlled release. They have shown a remarkable analgesic effect in the peripheral inflammatory pain areas.
authors.affiliation: Department of Anesthesiology, People's Hospital of Zhengzhou, Zhengzhou, 450000, China, lihongjunli1111@163.com.
authors.forename: Hongjun
authors.initials: H
authors.lastname: Li
authors.forename: Hui
authors.initials: H
authors.lastname: Qiao
authors.forename: Hongjie
authors.initials: H
authors.lastname: Lu
authors.forename: Changqi
authors.initials: C
authors.lastname: Liu
mesh_terms: D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D008055:Lipids / Q000737:chemistry; D008297:Male; D053758:Nanoparticles; D010146:Pain / Q000188:drug therapy*; D059408:Pain Management; D051381:Rats; D017207:Rats, Sprague-Dawley; D017409:Sufentanil / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D000701:Analgesics, Opioid; D008055:Lipids; D017409:Sufentanil