A question was whether it was preferable to give the reversal agent when profound block was present or wait for some spontaneous recovery before antagonizing the block. This study has been conducted to evaluate the reversal effects of neostigmine with divided doses in the rabbits after pancuronium when profound relaxation(PTC=O) or the first twitch of TOF stimulation was appeared (TOF,T1) was confirmed.

Rabbits(n=60) were randomly allocated to 5 groups. After pancuronium 0.2 mg/kg intravenously, spontaneous recovery was evaluated in group 1. When the profound relaxation(PTC=O) was confirmed at 5 min. after pancuronium, neostigmine 50 ug/kg with atropine 20 ug/kg were injected in group 2. At that time, neostigmine 10 ug/kg with atropine 4 ug/kg were injected and after 3 min. neostigmine 40 ug/kg with atropine 16 ug/kg were injected in group 3. When TOF, Tl was confirmed, neostigmine 50 ug/kg with atropine 20 ug/kg were injected in group 4. At that time, neostigmine and atropine were injected in group 5 as the same way of group 3.

The mean time from injection of pancuronium to 95% recovery was 98.9 min. in group 1, 60.3 min. in group 2, 50.9 min. in group 3, 71.0 min. in group 4 and 67.1 min. in group 5. The recovery index was significantly reduced when neostigmine was injected at TOF,T1(p<0.05). The recovery time after neostigmine with divided doses was reduced, but there was no significant difference.

The results of present study suggested that total recovery time was reduced when neostigmine was injected earlier with divided doses than single dose unrelated to profound relaxation.