TIME-COURSE OF NEUROMUSCULAR EFFECTS AND PHARMACOKINETICS OF ROCURONIUM BROMIDE (ORG-9426) DURING ISOFLURANE ANESTHESIA IN PATIENTS WITH AND WITHOUT RENAL-FAILURE

We have studied the onset and duration of action and pharmacokinetics of rocuronium bromide (Org 9426) during anaesthesia with nitrous oxide , fentanyl and isoflurane after a single bolus dose of rocuronium 0.6 mg kg-1 in nine patients with chronic renal failure requiring regular haemodialysis, and in nine healthy control patients. Blood samples wer e collected over 390 min and concentrations of rocuronium and its puta tive metabolites measured using HPLC. Onset time for maximum block, du ration of clinical relaxation (T1(25)) and recovery index, were 61 (SD 25.0) s and 65 (16.4) s, 55 (26.9) min and 42 (9.3) min and 28 (12.3) min and 19 (8.8) min, respectively, for patients with and without ren al failure. The time for TOF ratio to return spontaneously to 0. 7 was 99 (4 1. 1) min and 73 (24.2) min, respectively, in the two groups. N one of these differences was significant The pharmacokinetic data were best described by a three-exponential equation. There were significan t differences between patients with and without renal failure in the r ates of clearance (2.5 (1. 1) ml kg-1 min-1 and 3.7 (1.4) ml kg-1 min- 1, respectively) and the mean residence times (97.1 (48.7) min and 58. 3 (9.6) min) (P < 0.05). The differences in other kinetic parameters w ere not significant We conclude that the effects of rocuronium may be prolonged in patients with renal disease, because of a decreased clear ance of the drug.