title: Sensitivity to vecuronium in seropositive and seronegative patients with myasthenia gravis.
abstract: Patients with myasthenia gravis (MG) are hypersensitive to nondepolarizing neuromuscular blocking drugs. Although antibodies to the acetylcholine receptor (AChR) often are observed in MG patients, 10% to 30% of patients do not show an anti-AChR antibody. Little is known about differences in sensitivity to nondepolarizing neuromuscular blocking drugs between MG patients with and without anti-AChR antibody. Hypothesizing that seronegative patients are as sensitive to vecuronium as seropositive patients, we assessed sensitivity in seropositive and seronegative MG patients and in non-MG patients (n = 8 each). During anesthesia with sevoflurane (2.5%) and nitrous oxide (60%) in oxygen, neuromuscular transmission was monitored by measuring the twitch tension of the adductor pollicis muscle with supramaximal stimulation. After baseline measurements, 10 microg/kg IV dose increments of vecuronium were administered sequentially until blockade exceeded 90%. The degree of blockade and onset time after the initial 10 microg/kg of vecuronium were assessed, and doses required to exceed 90% blockade were recorded. In addition, effective doses of 50% and 95% for vecuronium were calculated from a single data point. Both types of MG patients showed increased sensitivity to vecuronium compared with non-MG patients.
  
  
  CONCLUSIONS
  Hypothesizing that seronegative patients are as sensitive to vecuronium as seropositive patients, we assessed sensitivity in seropositive and seronegative myasthenia gravis (MG) patients and in non-MG patients. They were, indeed, both equally sensitive to vecuronium.
authors.affiliation: Department of Anesthesiology and Intensive care Medicine, Kanazawa University School of Medicine, 13-1 Takara-machi, Kanazawa 920-8641, Japan. hironori@med.kanazawa-u.ac.jp
authors.forename: Hironori
authors.initials: H
authors.lastname: Itoh
authors.forename: Keizo
authors.initials: K
authors.lastname: Shibata
authors.forename: Shunichi
authors.initials: S
authors.lastname: Nitta
mesh_terms: D000328:Adult; D000368:Aged; D000758:Anesthesia; D002800:Cholinesterase Inhibitors; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000097:blood / Q000150:complications* / Q000276:immunology*; D003473:Neuromuscular Nondepolarizing Agents; D011729:Pyridostigmine Bromide; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D013945:Thymoma / Q000150:complications; D014673:Vecuronium Bromide
chemical_list: D002800:Cholinesterase Inhibitors; D003473:Neuromuscular Nondepolarizing Agents; D014673:Vecuronium Bromide; D011729:Pyridostigmine Bromide