Enflurane anesthesia and antipyrine metabolism.

To evaluate the influence of enflurane anesthesia on the hepatic drug-metabolizing capacity, antipyrine half-life was measured in 18 surgical patients before surgery and on days 4 and 8 after anesthesia. The effect of repeated administration of antipyrine on the rate of antipyrine metabolism was also evaluated in nine control subjects. Simultaneous measurement of plasma fluoride concentration allowed enflurane metabolism to be quantitated. Regardless of duration, enflurane anesthesia did not increase the rate of antipyrine metabolism as indicated by the absence of significant change in antipyrine half-life and clearance. Repeated doses of antipyrine to nine normal subjects did not influence the rate of antipyrine metabolism. Preanesthesia elimination rate of antipyrine did not indicate individual capacity to metabolize enflurane. Mean peak fluorides level (10.7 +/- 4.8 mM) was reached 3 hr after anethesia and did not appear to correlate with duration of exposure to enflurane.