Journal of Applied Physiology, Vol 62, Issue 5 1970-1974, Copyright © 1987 by American Physiological Society
Concentration-dependent interaction of theophylline with d-tubocurarine
N. Fuke, J. Martyn, C. S. Kim and S. Basta
The interaction of theophylline with d-tubocurarine chloride (dTC) was
examined in rabbits. After steady-state subtherapeutic (less than 10 mg/l),
therapeutic (10-20 mg/l), and toxic (greater than 20 mg/l) concentrations
of theophylline, dose-response curves for dTC were determined and compared
with controls that received no theophylline. At therapeutic concentrations
of theophylline the effective dose for 50% inhibition of twitch (ED50) for
dTC (mean +/- SE, 0.115 +/- 0.016 mg/kg) was significantly shifted to the
left in comparison with the control (0.165 +/-0.008 mg/kg). The ED50 of dTC
for the subtherapeutic group was 0.143 +/- 0.011 mg/kg, which was less than
the control but not of statistical significance (P = 0.1). The ED50 for the
toxic theophylline group was 0.168 +/- 0.003 mg/kg, which was not
significantly different from controls but significantly different from the
theophylline therapeutic and subtherapeutic groups. Thus, toxic
concentrations of theophylline reversed the potentiating effects of
therapeutic and subtherapeutic concentrations of dTC dose-response curves.
Therefore, depending on concentration, theophylline exhibits a biphasic
interaction with dTC. Surgical patients on theophylline may require less
dTC intraoperatively. More importantly, the use of theophylline in the
postoperative period to reverse anesthetic effects may result in
recurarization.
