Effect of pretreatment with oral pyridostigmine on subsequent activity of alcuronium in non-anaesthetized subjects.

Abstract

We have studied the effects of alcuronium in 10 healthy, non-anaesthetized volunteers after they had been taking oral pyridostigmine 30 mg 8 hourly. The responses of adductor pollicis were recorded using an isolated forearm procedure (IFP) during onset and recovery of neuromuscular block produced by 1.5 mg of relaxant. Previously noted disparities between mechanomyogram and electromyogram measurement of the first response of the train-of-four (T1) and the ratio of the fourth (T4) to the first response (TOF ratio) were found in most cases, but were unaffected by pyridostigmine. Pyridostigmine did not affect significantly the overall characteristics of neuromuscular block, but repeated IFP after a placebo unexpectedly produced marginally less depression of T1 and more rapid recovery. The hysteresis relationship between T1 and T4 during onset and recovery of block was confirmed, but was not affected by pyridostigmine. Clinically, the results may indicate that pyridostigmine pretreatment is unlikely to have significant effects on the subsequent use of alcuronium.