The lack of histamine release with cisatracurium: a double-blind comparison with vecuronium

A prospective, randomized, double-blind study was performed in 62 patients (ASA Classes I and II) treated with either 0.15 or 0.25 mg/kg cisatracurium or 0.15 mg/kg vecuronium administered as a rapid bolus. We wished to determine whether the muscle relaxants caused cutaneous, systemic, or chemical evidence of histamine release. Six minutes after induction of anesthesia with thiopental, patients received one of the muscle relaxants over 5 s. Plasma histamine levels were measured by radioimmunoassay after thiopental administration and 3 and 5 min after the administration of the relaxant. Additionally, plasma was assayed for tryptase, a marker of mast cell release. Cutaneous manifestations to both thiopental and the muscle relaxant were graded by an independent observer. Arterial blood pressure and heart rate were measured every minute. Although systolic and diastolic blood pressure decreased and heart rate increased significantly after thiopental administration (P < 0.0001), there were no further hemodynamic changes after either cisatracurium or vecuronium. One patient who received 0.25 mg/kg cisatracurium exhibited a slight elevation in plasma histamine level 5 min after hemodynamic changes. Cutaneous signs of histamine release were noted in five patients after thiopental administration (flush in four, erythema in one), but no further cutaneous reactions were observed after administration of either cisatracurium or vecuronium. We conclude that cisatracurium and vecuronium do not cause systemic or cutaneous histamine release. Tryptase levels showed no evidence of mast cell degranulation.