Is Enflurane Defluorination Inducible in Man?

Abstract

Serum inorganic fluoride levels and anesthetic exposure were measured in 102 surgical patients to determine the effects of enzyme-inducing drugs on euflurane metabolism. Serum electrolytes, urea N and creatinine values were also determined. Patients were classified into four groups according to their current drug-intake histories: control (no drug), 26 patients; chronic ethanol, 31 patients; chronic phenobarbital and/or phenytoin, 12 patients; miscellaneous drugs, 33 patients. None of the regression lines of peak serum fluoride on anesthetic exposure for the drug groups was significantly different from that of the control group. Five patients received enflurane anesthesia twice, with the regression line for the 2nd exposure not significantly different from that for the 1st. Mean peak serum fluoride level for all patients was 17.7 .+-. 0.8 .mu.M, with the highest individual value in the study, 44.7 .mu.M, occurring in a control patient. Electrolyte, urea N, and creatinine values remained normal throughout the experiment. Prior treatment with enzyme-inducing drugs does not increase enflurane defluorination in surgical patients, nor does it increase the risk of developing fluoride nephropathy.