Evolution of single twitch and train-of-four responses and of tetanic fade in relation to plasma concentrations of fazadinium in man

The evolution of single twitch and train-of-four (2 Hz) responses and tetanic fade (100 Hz) in relation to plasma concentration of fazadinium was determined during stable anesthesia (fentanyl-N2O) in six healthy adult patients after a bolus injection of 0.75 mg/kg of fazadinium. The interval between injection and 50% recovery and the corresponding fazadinium plasma concentrations were (mean +/- SEM): 47 +/- 4 minutes and 1.44 +/- 0.18 microgram/ml for the single twitch; 66 +/- 7 minutes and 1.01 +/- 0.10 microgram/ml for the train-of-four; and 83 +/- 11 minutes and 0.82 +/- 0.08 microgram/ml for tetanic fade. The results indicate that train-of-four and tetanic fade are more sensitive tests for evaluation of residual neuromuscular block than is measurement of single twitch responses.