Thransfer of mepivacaine from the placenta was studied in terms of total and freelevels in 17 pregnant women who received epidural anesthesia during cesarean-section.
Concentrations of mepivacaine in maternal and umbilical venous blood weredetermined by gas chromatography.
The umbilical/maternal (U/M) concentration ratio of total mepivacaine and that offree mepivacaine were 0.53±0.14 (mean±SD) and 0.73±0.21, respectively.
The protein binding ratio of mepivacaine in umbilical blood was significantly (P<0.01) lower than that in maternal blood.
This result suggests the importance of determining the free level of mepivacaine forconsidering the pharmacological effects on the fetus.
