title: Interaction between mivacurium and pancuronium: impact of the order of administration.
abstract: BACKGROUND
  Potentiation of mivacurium by low-dose pancuronium is mostly due to an inhibition of plasma butyryl cholinesterase (BchE) resulting in a decreased rate of hydrolysis of mivacurium. Nevertheless, an interaction at the receptor site could not be ruled out. By changing the order of the muscle relaxant injections, we may lessen the pharmacokinetic interaction and assess the impact at the acetylcholine receptor level.
  
  
  METHODS
  Twenty patients scheduled for general anesthesia with propofol and fentanyl, and isoflurane were randomized into two groups receiving, mivacurium 100 microg kg-1 followed by pancuronium 15 microg kg-1 (group 1) or pancuronium 15 microg kg-1 followed by mivacurium 100 microg kg-1 (group 2). BchE before and after injection of each relaxant was measured. Neuromuscular block was assessed with a force transducer at the adductor pollicis measuring the elicited twitch to ulnar nerve stimulation.
  
  
  RESULTS
  The neuromuscular block was greater when pancuronium was administered before mivacurium (100% versus 96+/-3%; P<0.05). Times to recovery of the elicited twitch response to 25% and 75% of control value were increased by 100% (P<0.05). After pancuronium, decreases in BchE of 11% and 14% in groups 1 and 2 were observed, respectively.
  
  
  CONCLUSIONS
  Interaction between mivacurium and low dose pancuronium is significant only when mivacurium is injected after pancuronium.
authors.affiliation: Service d'Anesthésie réanimation, Hôpital Henri-Mondor, APHP, Creteil, France. motamed@igr.fr
authors.forename: C
authors.initials: C
authors.lastname: Motamed
authors.forename: K
authors.initials: K
authors.lastname: Kirov
authors.forename: X
authors.initials: X
authors.lastname: Combes
authors.forename: P
authors.initials: P
authors.lastname: Feiss
authors.forename: P
authors.initials: P
authors.lastname: Duvaldestin
mesh_terms: D000368:Aged; D002091:Butyrylcholinesterase / Q000097:blood; D003627:Data Interpretation, Statistical; D004334:Drug Administration Schedule; D004347:Drug Interactions; D004359:Drug Therapy, Combination; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D006801:Humans; D007546:Isoquinolines / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D000077590:Mivacurium; D019148:Neuromuscular Blockade / Q000379:methods; D003473:Neuromuscular Nondepolarizing Agents / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000627:therapeutic use; D010197:Pancuronium / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000627:therapeutic use; D013997:Time Factors
chemical_list: D007546:Isoquinolines; D003473:Neuromuscular Nondepolarizing Agents; D000077590:Mivacurium; D002091:Butyrylcholinesterase; D010197:Pancuronium