The ulinastatin-induced effect on neuromuscular block caused by vecuronium

We examined the effect of ulinastatin, a protease inhibitor purified from human urine, on neuromuscular block caused by vecuronium. Sixty adult patients were randomly divided into four groups of 15 patients each: ulinastatin-posttetanic count (U-PTC), ulinastatin-train-of-four (U-TOF), control-posttetanic count (C-PTC) or control-train-of-four (C-TOF) group. In the U-PTC and U-TOF groups, a bolus dose of ulinastatin 5000 U/kg was administered 2 min before the injection of vecuronium 0.1 mg/kg. In the C-PTC and C-TOF groups, normal saline was administered instead of ulinastatin. The onset of neuromuscular block in the U-PTC and U-TOF groups was significantly slower than in the C-PTC and C-TOF groups (250+/-49 vs 214+/-35 s, mean +/- SD, P < 0.05). The time from the vecuronium injection to the return of PTC in the U-PTC group was significantly shorter than in the C-PTC group (11.0+/-2.8 vs 17.6+/-6.8 min, P < 0.05). Similarly, times to the returns of T1, T2, T3, and T4 (first, second, third, and fourth stimulation of TOF) in the U-TOF group were significantly shorter than in the C-TOF group (18.5+/-5.0 vs 28.0+/-9.1 min for T1, P < 0.05). PTC in the U-PTC group was significantly higher than in the C-PTC Group 10-30 min after the administration of vecuronium (P < 0.05). T1/control twitch height and TOF ratios in the U-TOF group were significantly higher than those in the C-TOF Group 30-70 min and 40-70 min after the administration of vecuronium, respectively (P < 0.05). Ulinastatin delays the onset of neuromuscular block and hastens its recovery caused by vecuronium.

Ulinastatin delays the onset of neuromuscular block and hastens its recovery caused by vecuronium. This is because ulinastatin may release acetylcholine at the neuromuscular junction and increase hepatic and/or renal clearance of vecuronium.