DOSE-RESPONSE AND TIME-COURSE OF EFFECT OF ROCURONIUM IN MALE AND FEMALE ANESTHETIZED PATIENTS

To determine differences frorn dose-response and time-course of rocuro nium between male and female patients, 60 adult patients (30 male and 30 female), ASA grade I, aged 17-52 yr, undergoing elective plastic su rgery were studied. Anesthesia was maintained with 60% nitrous oxide i n oxygen, thiopental, and incremental doses of fentanyl as required. N euromuscular function was assessed mechanomyographically with train-of -four (TOF) stimulation at the wrist every 12 s, and the percentage de pression of the T-1 response was used as the study variable. The dose- response relationship of rocuronium was determined by a cumulative dos e-response technique. The results showed that the dose-response curve of rocuronium in the men was shifted to the right, indicating a decrea se in the sensitivity to rocuronium-induced neuromuscular block versus the women. The 50%, 90%, and 95% effective doses of rocuronium were 1 78.4 +/- 53.7, 358.7 +/- 101.3, and 386.2 +/- 113.4 mu g/kg, respectiv ely, in male patients, and 128.8 +/- 42.5, 252.8 +/- 51.7, and 274.4 /- 59.4 mu g/kg in female patients. After an intravenous administratio n of total dose of 400 mu g/kg rocuronium, neuromuscular block was sig nificantly longer in the men than in the women. The duration of peak e ffect, clinical duration, and total duration were 6.5 +/- 3.0,12.5 +/- 4.9, and 33.6 +/- 8.7 min, respectively, in male patients, and 11.8 /- 2.7, 18.5 +/- 5.3, and 46.8 +/- 9.6 min in female patients. We conc lude that women were approximately 30% more sensitive to rocuronium co mpared with men. Implications: The authors found that women were 30% m ore sensitive to rocuronium than men. This suggests that the routine d ose of rocuronium should be reduced in women compared with men.