We describe a simple, rapid procedure for the estimation of carbamazepine in plasma. Protein is precipitated, and extraction is achieved by the addition of acetonitrile containing the internal standard N-acetyltryptophan ethyl ester. Separation is by reverse-phase high-pressure liquid chromatography with an acetonitrile: water mobile phase, and detection is by UV absorption at 280 nm. Total retention time is less than 7 minutes. Initial results gave within-batch and between-batch coefficients of variation of less than 2 %, and mean recovery of 97 %. The method is free from interference by other common anticonvulsant drugs.
References
1.
BurnettD.ValmanH. B.WorthH. G. J. (1978). SI units and anticonvulsant drugs in paediatrics. British Medical Journal, 2, 1207–1208.
2.
ChambersR. E.CameronJ. D. (1977). N-Acetyl-tryptophan ethyl ester: A new internal standard for the gas chromatographic determination of plasma anticonvulsant levels. Annals of Clinical Biochemistry, 14, 243.
3.
FrielP.GreenJ. R. (1973). Quantitative assay for carbamazepine serum levels by gas-liquid chromatography. Clinica Chimica Acta, 43, 69–72.
4.
FrigerioA.BakerK. M.BelvedereG. (1973). Gas chromatographic degradation of several drugs and their metabolites. Analytical Chemistry, 45, 1846–1851.
5.
HouseI. M.BerryD. J. (1976). Analysis of carbamazepine in plasma by high-pressure liquid chromatography. In High-pressure Liquid Chromatography in Clinical Chemistry, edited by DixonP. F.GrayC. H.UrnC. K.StollM. S., Academic Press: New York.
6.
KabraP.M.StaffordB. E.MartonL. J. (1977). Simultaneous measurement of phenobarbital, phenytoin, primidone, ethosuximide and carbamazepine in serum by high-pressure liquid chromatography. Clinical Chemistry, 23, 1284–1288.
7.
MihalyG. W.PhillipsJ. A.LouisW. J.VajdaF. J. (1977). Measurement of carbamazepine and its epoxide metabolite by high-performance liquid chromatography, and a comparison of assay techniques for the analysis of carbamazepine. Clinical Chemistry, 23, 2283–2287.
8.
MorselliP. L.FrigerioA. (1975). Metabolism and pharmacokinetics of carbamazepine. Drug Metabolism Reviews, 4, 97–113.
9.
WestenbergH. G. M.De ZeeuwR. A. (1976). Rapid and sensitive liquid chromatographic determination of carbamazepine suitable for use in monitoring multiple-drug anticonvulsant therapy. Journal of Chromatography, 118, 217–224.
