title: Ketamine potentiates nondepolarizing neuromuscular relaxants in a primate.
abstract: Ketamine has many neuromuscular effects in vitro. Its neuromuscular effects in vivo have been controversial and inconsistent. To systematically examine its neuromuscular effects over a wide dose range and its interaction with all popular nondepolarizing neuromuscular relaxants, the effects of ketamine 2, 5, and 10 mg/kg IV were studied on a continuous but incomplete (50%) neuromuscular block preestablished by an IV infusion of d-tubocurarine, atracurium, vecuronium, and pancuronium. Indirectly stimulated adductor pollicis muscle response of monkeys anesthetized with 0.5-1.0% halothane in oxygen were quantified. Ketamine in the absence of a neuromuscular relaxant had no effect on the thumb twitch. In a dose-dependent manner, ketamine significantly enhanced the 50% depression of the thumb twitch preestablished by a constant IV infusion of each of the four muscle relaxants studied. Ketamine 2 mg/kg potentiated the neuromuscular relaxants in the following order of magnitude: vecuronium greater than atracurium greater than d-tubocurarine greater than pancuronium. However, with a 10 mg/kg dose of ketamine, pancuronium became as potentiated as was vecuronium, i.e., pancuronium = vecuronium greater than atracurium greater than d-tubocurarine. It is concluded that in the primate, ketamine potentiates all nondepolarizing muscle relaxants in a dose-dependent manner.
authors.affiliation: Department of Anesthesiology, National Yang-Ming Medical College, Veterans General Hospital, Taipei, Taiwan, Republic of China.
authors.forename: S K
authors.initials: SK
authors.lastname: Tsai
authors.forename: C
authors.initials: C
authors.lastname: Lee
mesh_terms: D000818:Animals; D001279:Atracurium / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D007649:Ketamine / Q000494:pharmacology*; D008251:Macaca; D008297:Male; D009469:Neuromuscular Junction / Q000187:drug effects*; D010197:Pancuronium / Q000494:pharmacology*; D013933:Thumb; D014403:Tubocurarine / Q000494:pharmacology*; D014673:Vecuronium Bromide / Q000494:pharmacology*
chemical_list: D001279:Atracurium; D007649:Ketamine; D014673:Vecuronium Bromide; D010197:Pancuronium; D014403:Tubocurarine