The effect of residual receptor occupancy on sensitivity to repeated vecuronium.
Cumulative dose-response curves were obtained for vecuronium in 10 patients anaesthetised with thiopentone, enflurane and nitrous oxide using adductor pollicis mechanomyography. Five patients received vecuronium systemically, which was repeated at 100% twitch recovery to obtain initial and repeat curves. Another five patients received 0.3 mg vecuronium into an isolated forearm and at 100% recovery of this arm received vecuronium systemically to obtain simultaneous dose-response curves in both the previously isolated and nonisolated arms. There was no significant difference between the calculated ED50 obtained after initial systemic administration [16.2 (1.7) micrograms.kg-1], after recovery in the previously isolated arm [14.8 (2.0) micrograms.kg-1] and simultaneously in the nonisolated arm [16.1 (2.9) micrograms.kg-1]. The ED50 obtained after repeated systemic administration was significantly reduced [8.2 (2.9) micrograms.kg-1]. These results suggest that the reduction in ED50 at 100% twitch recovery from systemic vecuronium is not due to residual drug at the biophase/receptor but to drug persisting in the plasma.
Campkin
N T
NT
Magill Department of Anaesthetics, Chelsea and Westminster Hospital, London.
Hood
J R
JR
Fauvel
N J
NJ
Feldman
S A
SA
D000768:Anesthesia, General; D004305:Dose-Response Relationship, Drug; D004342:Drug Hypersensitivity / Q000097:blood*; D005260:Female; D005542:Forearm; D006801:Humans; D009119:Muscle Contraction / Q000187:drug effects*; D011897:Random Allocation; D011955:Receptors, Drug / Q000187:drug effects; D014459:Ulnar Nerve / Q000502:physiology; D014673:Vecuronium Bromide / Q000097:blood / Q000494:pharmacology*
D011955:Receptors, Drug; D014673:Vecuronium Bromide