title: Ifenprodil for prolonged spinal blockades of motor function and nociception in rats.
abstract: BACKGROUND
  The aim of the study was to compare the proposed spinal anesthetic effect of ifenprodil, an a1 adrenergic receptor antagonist, with that of the long-acting local anesthetic bupivacaine.
  
  
  METHODS
  After intrathecally injecting the rats with five different doses of each drug, the dose-response curves of ifenprodil and bupivacaine were constructed to obtain the 50% effective dose (ED50). The spinal blockades of motor function and nociception of ifenprodil were compared with that of bupivacaine.
  
  
  RESULTS
  We showed that either ifenprodil or bupivacaine produced spinal blockades of motor function and nociception dose-dependently. On the ED50 basis, the potency of ifenprodil (0.42(0.38-0.46) μmol; 0.40(0.36-0.44) μmol) was equal (p>0.05) to that of bupivacaine (0.38(0.36-0.40) μmol; 0.35(0.32-0.38) μmol) in motor function and nociception, respectively. At the equianesthetic doses (ED25, ED50, and ED75), duration produced by ifenprodil was greater than that produced by bupivacaine in motor function and nociception (p<0.05 for the differences). Furthermore, both ifenprodil and bupivacaine showed longer duration of sensory blockade than that of motor blockade (p<0.05 for the differences).
  
  
  CONCLUSIONS
  The resulting data demonstrated that ifenprodil produces a dose-dependent local anesthetic effect in spinal anesthesia. Ifenprodil shows a more sensory-selective duration of action over motor block, whereas the duration of anesthesia is significantly longer with ifenprodil than with bupivacaine.
authors.affiliation: Department of Physical Therapy, College of Health Care, China Medical University, Taichung, Taiwan; Department of Medical Research, Chi Mei Medical Center, Tainan, Taiwan.
authors.forename: Yu-Wen
authors.initials: YW
authors.lastname: Chen
authors.affiliation: Department of General Surgery, Chi Mei Medical Center, Tainan and Liouying, Taiwan; Department of Electrical Engineering, Southern Taiwan University of Science and Technology, Tainan, Taiwan.
authors.forename: Chong-Chi
authors.initials: CC
authors.lastname: Chiu
authors.affiliation: Department of Pediatrics, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Jieh-Neng
authors.initials: JN
authors.lastname: Wang
authors.affiliation: Department of Physical Therapy, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Institute of Allied Health Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan. Electronic address: chhung@mail.ncku.edu.tw.
authors.forename: Ching-Hsia
authors.initials: CH
authors.lastname: Hung
authors.affiliation: Department of Medical Research, Chi Mei Medical Center, Tainan, Taiwan.
authors.forename: Jhi-Joung
authors.initials: JJ
authors.lastname: Wang
mesh_terms: D000775:Anesthesia, Spinal / Q000379:methods; D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D002045:Bupivacaine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D007278:Injections, Spinal / Q000379:methods; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D009407:Nerve Block / Q000379:methods; D059225:Nociception / Q000187:drug effects*; D010880:Piperidines / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000779:Anesthetics, Local; D010880:Piperidines; C010739:ifenprodil; D002045:Bupivacaine
keywords: Bupivacaine; Ifenprodil; Motor function; Nociception; Spinal block