Assessment of drug concentrations in tears in therapeutic drug monitoring: I. Determination of valproic acid in tears by gas chromatography/mass spectrometry with EC/NCI mode.
A rapid and sensitive method for the quantitation of valproic acid in tears has been developed using gas chromatography/electron capture negative chemical ionization/mass spectrometry. Valproic acid was converted directly into its pentafluorobenzyl ester derivative without the need to perform any extraction from the biologic fluid. The concentrations in tears [C]t correlated very well with those of the free form in the plasma [Cf]p and those of the total form in the plasma [Cb+f]p. The ratios between valproic acid concentrations in tears and plasma were as follows: [C]t/[Cb+f]p = 0.10 +/- 0.02; [C]t/[Cf]p = 0.57 +/- 0.11. Ratios of [C]t/[Cb+f]p were in good agreement with previously published data.
Nakajima
M
M
Department of Anaytical Chemistry, Niigata College of Pharmacy, Japan.
Yamato
S
S
Shimada
K
K
Sato
S
S
Kitagawa
S
S
Honda
A
A
Miyamoto
J
J
Shoda
J
J
Ohya
M
M
Miyazaki
H
H
D000927:Anticonvulsants / Q000032:analysis*; D002138:Calibration; D016903:Drug Monitoring / Q000379:methods; D004827:Epilepsy / Q000097:blood / Q000188:drug therapy / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D012680:Sensitivity and Specificity; D013666:Tears / Q000737:chemistry*; D014635:Valproic Acid / Q000032:analysis* / Q000097:blood
D000927:Anticonvulsants; D014635:Valproic Acid