Urinary, biliary and faecal excretion of rocuronium in humans

The excretion of rocuronium and its potential metabolites was studied in 38 anaesthetized patients, ASA I-III and 21-69 yr old. Rocuronium bromide was administered as an i.v. bolus dose of 0.3 or 0.9 mg kg(-1). in Part A of t he study, the excretion into urine and bile, and the liver content were stu died. Plasma kinetics (n=19) were similar to those reported previously. Uri nary recovery within 48 h after administration was 26 (8)% (mean (SD)) (n=8 ) of the dose. In bile obtained from T-drains, the recovery within 48 h was 7 (6)% (n=11). The rocuronium concentration in bile declined bi-exponentia lly, with half-lives of 2.3 (0.7) and 16 (11) h respectively (n=6). In thre e patients from whom stoma fluid was collected, the amount of rocuronium re covered ranged from 0.04 to 12.0% of the dose. In liver tissue obtained fro m four patients undergoing hemihepatectomy, the estimated amount of rocuron ium at 2-5 h after administration ranged between 6.3 and 13.2% (n=4). In th e second part of the study (Part B), urine and faeces were collected over 4 -8 days and the recovery was 27 (13)% and 31 (23)% of the dose respectively (n=10). In most samples, irrespective of the type of biological material, only small amounts of the metabolite 17-desacetyl-rocuronium was found. The results demonstrate that rocuronium is taken up by the liver and excreted into bile in high concentrations. The faecal and urinary excretion of uncha nged rocuronium are the major routes of rocuronium elimination.