Neuromuscular effects of rocuronium in patients receiving beta-adrenoreceptor blocking, calcium entry blocking and anticonvulsant drugs.

We have studied the onset and duration of action of rocuronium 0.6 mg kg-1 in patients receiving therapy for more than 1 month with beta-receptor blocking drugs (n = 16), calcium entry blocking drugs (n = 17) or anticonvulsant drugs (n = 14) and compared these data with those from a control group (n = 27). Anaesthesia comprised fentanyl, propofol infusion and nitrous oxide in oxygen. Neuromuscular block was monitored by measuring the force of contraction of the adductor pollicis muscle in response to train-of-four (TOF) stimulation. There were no significant differences in onset times between the four groups (mean 62-76 s). Mean times to 25% recovery of T1 (first response in the TOF) and of the TOF ratio of 0.7 were 38 (SD 15) and 58 (22) min, 36 (8) and 61 (19) min, 40 (11) and 68 (22) min, and 25 (6) and 35 (9) min in the control, beta-blocker, calcium entry blocker and anticonvulsant groups, respectively (P < 0.01 between the anticonvulsant and other groups). We conclude that chronic therapy with anticonvulsant drugs reduces the duration of action of rocuronium.