thiopental and laudanosine

Cisatracurium, one of the ten isomers in atracurium, is a nondepolarizing muscle relaxant with an intermediate duration of action. It is more potent and less likely to release histamine than atracurium. As one of the isomers composing atracurium, it presumably undergoes Hofmann elimination. This study was conducted to describe the pharmacokinetics of cisatracurium and its metabolites and to determine the dose proportionality of cisatracurium after administration of 2 or 4 times the ED(95).. Twenty ASA physical status 1 or 2 patients undergoing elective surgery under nitrous oxide/opioid/barbiturate anesthesia were studied. Patients received a single rapid intravenous bolus does of 0.1 or 0.2 mg x kg-1 (2 or 4 times the ED(95), respectively) cisatracurium. All patients were allowed to recover spontaneously to a train-of-four ratio > or = 0.70 after cisatracurium-induced neuromuscular block. Plasma was extracted, acidified, and stored frozen before analysis for cisatracurium, laudanosine, the monoquaternary acid, and the monoquaternary alcohol metabolite.. The clearances (5.28 +/- 1.23 vs. 4.66 +/- 0.67 ml x min(-1) x kg(-1) and terminal elimination half-lives (22.4 +/- 2.7 vs. 25.5 +/- 4.1 min) were not statistically different between patients receiving 0.1 mg x kg(-1) and 0.2 mg x kg(-1), respectively. Maximum concentration values for laudanosine averaged 38 +/- 21 and 103 +/- 34 ng x ml(-1) for patients receiving the 0.1 and 0.2 mg x kg(-1) doses, respectively. Maximum concentration values for monoquaternary alcohol averaged 101 +/- 27 and 253 +/- 51 ng x ml(-1), respectively. Monoquaternary acid was not quantified in any plasma sample.. Cisatracurium undergoes Hofmann elimination to form laudanosine. The pharmacokinetics of cisatracurium are independent of dose after single intravenous doses of 0.1 and 0.2 mg x kg(-1).

Topics: Adult; Aged; Anesthetics, Inhalation; Anesthetics, Intravenous; Atracurium; Female; Fentanyl; Humans; Isoquinolines; Male; Midazolam; Middle Aged; Neuromuscular Nondepolarizing Agents; Nitrous Oxide; Opium; Stereoisomerism; Thiopental

Twenty patients were given maximal doses of atracurium or vecuronium by infusion during surgery. Anaesthesia was maintained with an infusion of thiopentone, nitrous oxide and fentanyl. In patients administered atracurium, the plasma laudanosine concentration at cessation of surgery was 0.34 (SD 0.22) micrograms ml-1; there was little tendency to cumulate during operation. A 20% higher arterial concentration of thiopentone was found at awakening in patients given atracurium, suggesting CNS stimulation by laudanosine, although the effect is too modest to be of clinical significance.

Topics: Anesthesia Recovery Period; Anesthesia, General; Atracurium; Brain; Humans; Isoquinolines; Middle Aged; Thiopental; Time Factors

The anaesthetic management of a patient whose giant cerebral aneurysm was clipped is described. Profound hypothermia and thiopentone were used to provide cerebral protection during circulatory arrest. Atracurium was used to provide muscle relaxation; the level of neuromuscular block and plasma concentrations of atracurium and laudanosine were measured.

Topics: Adult; Anesthesia, General; Atracurium; Female; Fentanyl; Heart Arrest, Induced; Humans; Hypothermia, Induced; Intracranial Aneurysm; Isoflurane; Isoquinolines; Thiopental