title: Assessing the use of 50% enantiomeric excess bupivacaine-loaded microspheres after sciatic nerve block in rats.
abstract: OBJECTIVE
  To achieve better therapeutic benefits of local anesthetics in the control of postoperative pain through controlled-release carrier. The objective of this study was to compare the characteristics of sensory and motor blockade between microspheres without local anesthetic: racemic bupivacaine-loaded microspheres; 50% enantiomeric excess bupivacaine-loaded microspheres; and free 50% enantiomeric excess bupivacaine.
  
  
  METHODS
  Wistar rats were distributed into four groups: A (Microsphere); B (S50-R50 bupivacaine-loaded microsphere); C (50% enantiomeric excess bupivacaine-loaded microsphere); and D (50% enantiomeric excess bupivacaine). Inhalation anesthesia was performed before the sciatic nerve block (2% halothane and 100% O(2)). Sensorial blockade was measured by the time required for each rat to withdraw its paw from a hot plate at 56°C (positive>4 sec). Motor blockade was measured by the time between drug injection until recovery of a motor score of 2 on the established criterion.
  
  
  RESULTS
  The sensory response was significantly more frequent in groups B, C, and D than in group A (p<0.001). There were no statistically significant differences in the response to the sensory test in groups B, C, and D (p>0.05). The response to the motor test was also significantly more frequent in groups B, C, and D than in group A (p=0.02). A tendency to greater positivity in the motor test was more frequently found in groups B and D than in group C (p=0.10).
  
  
  CONCLUSIONS
  Controlled-release of 50% enantiomeric excess bupivacaine-loaded microspheres showed similar results regarding analgesia and less motor blockade when compared to other anesthetic formulations.
authors: Universidade Federal do Paraná, Anesthesiologist of Hospital Nossa Senhora das Graças.
authors: Rohnelt Machado
authors: RM
authors: de Oliveira
authors: Pedro Paulo
authors: PP
authors: Tanaka
authors: Sergio Bernardo
authors: SB
authors: Tenorio
mesh_terms: D000779:Anesthetics, Local / Q000008:administration & dosage*; D000818:Animals; D002045:Bupivacaine / Q000008:administration & dosage*; D004337:Drug Carriers; D008297:Male; D008863:Microspheres; D009407:Nerve Block; D051381:Rats; D017208:Rats, Wistar; D012584:Sciatic Nerve
chemical_list: D000779:Anesthetics, Local; D004337:Drug Carriers; D002045:Bupivacaine