Dose-response relationships for a 1:4 weight ratio-mixture of
pancuronium and
metocurine were studied during inhalational
anesthesia with
halothane and
isoflurane in patients with and without
renal failure. The time for recovery from 10 to 20% of control thumb twitch tension also was determined. In subjects with normal renal function, relaxant doses required for 95% twitch height suppression (ED95) were 50% of those predicted by simple addition of effects when used with a balanced
anesthetic technique, 37% of predicted when used with 1.3 MAC
halothane, and 25% of predicted when used with 1.3 MAC
isoflurane (P less than 0.05). In subjects with
renal failure, ED95 values for the combination were 40% of predicted when used with 1.2 MAC
halothane and 45% of predicted when used with 1.2 MAC
isoflurane (NS). For relaxants used singly in
renal failure,
pancuronium alone was slightly enhanced by 1.2 MAC
halothane (85% of predicted), while 1.1 MAC
isoflurane reduced the ED95 to 57% of predicted (P less than 0.05). Similar results were obtained for
metocurine alone when used in
renal failure (77 and 58% of predicted when used with
halothane and
isoflurane, respectively) (NS). Predicted values are published results for
balanced anesthesia in normals. Recovery times were prolonged twofold in
renal failure (P less than 0.05). Thus, the combination of
pancuronium and
metocurine is synergistic to the same degree in normals and in
renal failure patients, but the total blockade produced by the combination is enhanced by
halothane and
isoflurane only in normals.