[Time course of neuromuscular blockade after rocuronium. A comparison between women and men]

We studied 40 patients (20 female and 20 male) undergoing elective surgery under general anaesthesia to evaluate the effect of gender on the pharmacodynamics of rocuronium.

Using electromyography (EMG) we determined the maximal neuromuscular block and time course of action of 0.45 mg/kg rocuronium (1.5 x ED95).

Age and body mass index were comparable between females and males (38 (+/- 8) vs. 37 (+/- 10) years and 24.2 (+/- 2.9) vs. 25.2 (+/- 1.7) kg/m2. However, significant differences in weight and height were found between females and males (65.7 +/- 9.3 kg vs. 77.5 +/- 5.5 kg; p < 0.01 and 178 +/- 6.8 cm vs. 164 +/- 6.7 cm; p < 0.01). Onset time was shorter in females (168 +/- 65 s vs. 211 +/- 56 s; p < 0.05). Maximal neuromuscular blockade after 0.45 mg/kg rocuronium was 94 (+/- 3) % in females and 89 (+/- 6) % in males; p < 0.01. Clinical duration was increased in females (23 +/- 5 min vs. 17 +/- 5 min; p < 0.05), while the recovery index was comparable between both groups (9 +/- 4 min in females and 9 +/- 3 min in males; n.s.).

Compared to men neuromuscular blockade after 0.45 mg/kg rocuronium was more pronounced in women. The onset time was shortened and the clinical duration increased in female patients.