Effect of smoking on dose requirements for vecuronium.

We have compared the potency of vecuronium given to 12 smokers and 12 non-smokers during propofol-alfentanil-nitrous oxide anaesthesia. After obtaining individual dose-response curves, bolus doses of vecuronium were given to maintain neuromuscular block at 90-98% for 60 min. Adductor pollicis EMG was used to monitor neuromuscular block. Mean ED95 values were 61.38 micrograms kg-1 and 47.49 micrograms kg-1 for smokers and non-smokers, respectively (P < 0.01). The dose of vecuronium to maintain 90-98% neuromuscular block was 25% higher in smokers than in non-smokers (96.80 vs 72.11 micrograms kg-1 h-1; P < 0.01). These data reflect the effects of smoking on neuromuscular block induced by vecuronium. The effect may be at the receptor level, although possible increased metabolism of vecuronium in smokers cannot be excluded.