Quantitative determination of carbamazepine in plasma by mass fragmentography

Abstract

A specific and sensitive method for the quantitative determination of carbamazepine in plasma by combined gas chromatography‐mass spectrometry (mass fragmentography) has been developed. 10,11‐Dihydrocarbamazepine was synthesized and used as an internal standard. With this method only one extraction step is needed and derivatization is unnecessary. Eighty to one hundred analyses can be performed per day. The standard deviation of the method is ± 0.08 above, and ± 0.02 p.g per milliliter below 1 µg carbamazepine per milliliter plasma, respectively. Concentrations of carbamazepine can be accurately determined down to 50 ng per milliliter using 0.5 ml of plasma for analysis. In a pilot volunteer study two subjects each received a single oral dose of 200 mg carbamazepine, and the plasma level of the drug was followed for 7 days. The half‐lifes (35 and 37 hours) and volumes of distribution (1.3 L per kilogram in both) were similar in both.