Effects of Neostigmine , Pyridostigmine and Edrophonium on Plasma Cholinesterase Activity and Train-of-four Response

Kim, Sun Chong; Hwang, Kyung Ho; Kim, Sung Yell

Abstract

Effects of the anticholinesterase drugs on plasma cholinesterase activity, plasma albumin level and train-of-four response were investigated in 38 ASA class 1 or 2 adult patients undergoing elective surgery. Anesthesia was induced with thiopental sodium 5~6 mg/kg followed by succinylcholine 1 mg/kg to facilitated tracheal intubation, and was maintained with O2-N2O(50%)-enflurane (1~2%). For maintenance of adequate muscle relaxation, initial bolus (0.08 mg/kg) and small incremental doses (0.02~0.04 mg/kg) of vecuronium were administered. At the end of surgery, neuromuscular blockade was reversed with neostigmine 0.04 mg/kg as a single bolus dose (neostigmine group, n=10), divide dose of neostigmine (20%:80%, neostigmine-divide group, n=10), pyridostigmine 0.2mg/kg (pyridostigmine group, n=10), or edrophonium 0.5mg/kg (edrophonium group, n=8) respectively. Reversal was attempt at 10% spontaneous recovery of first twitch height (T1), which was measured using train-of-four (TOF) stimulation of ulnar nerve repeated every 20 seconds (EMG, Datex co.). The results obtained were as follows: 1) Neostigmine, neostigmine-divide and pyridostigmine groups all produced markedly inhibition of plasma cholinesterase activity which was maximum at 5 minutes after injection, and was persisted significantly for 60 miuntes in both neostigmine and neostigmine-divide groups, and for 120 minutes in pyridostigmine group. The inhibition of plasma cholinesteraae was correlated significantly with TOF recovery in all groups except in edrophonium group. There was no inhibition of enzymatic activity up to 30 minutes in edrophonium group. 2) The changes in plasma albumin level after administration of anticholinesterase drugs were insignificant in all groups. 3) Both T1 and the ratio of the 4th twitch height to T1 (T4 ratio) were recovered above 75% of control within 30 minutes after injection of each anticholinesterase drugs in all groups, but there was significant slow progressing in edrophonium group. Comparing with same height of T1 the T4 ratio was not greater in edrophonium than in neostigmine or pyridostigmine. 4) The simultaneous administration of anticholinesterase drug and atropine (0.02 mg/kg) resulted the minimal changes in mean arterial pressure (+/-7% compared with prior to injection) or heart rate (+/-10% compared with prior to injection) from 5 minutes to 60 minutes after injection in all groups. In conclusion, although it was not thought that enzyme inhibition may be the sole factor, it should be considered to use succinylcholine or ester type of local anesthetics in patients who had recently received anticholinesterase drugs for reversal of nondepolarizing neuromuscular blockade, or for treatment of myasthenia gravis and glaucoma.