Sensitivity to vecuronium in seropositive and seronegative patients with myasthenia gravis.
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.
Itoh
Hironori
H
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
Shibata
Keizo
K
Nitta
Shunichi
S
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
D002800:Cholinesterase Inhibitors; D003473:Neuromuscular Nondepolarizing Agents; D014673:Vecuronium Bromide; D011729:Pyridostigmine Bromide