Determination of dolasetron and its reduced metabolite in human plasma by GC-MS and LC.

Both a GC-MS and an LC method have been developed for the simultaneous quantitation of dolasetron and reduced dolasetron in human plasma. The GC-MS method has been utilized in preliminary human pharmacokinetic studies of dolasetron mesylate. Selected ion monitoring was used in these initial studies to obtain the sensitivity and specificity required for quantitation. The GC-MS method has been used in the range of 1-120 ng ml-1 for dolasetron and 1-240 ng ml-1 for reduced dolasetron in plasma. The limit of quantitation for both compounds by GC-MS was 1 ng ml-1. Recently, an LC method has been utilized for quantitation of both compounds on a routine basis. This method utilizes essentially the same sample preparation procedure as the GC-MS method. The LC method has been used in the range of 5-200 ng ml-1 in plasma for dolasetron and reduced dolasetron. In addition, the relationship between the LC and GC-MS methods has been assessed using data obtained from human male volunteers following intravenous administration of 3.0 mg kg-1 of dolasetron mesylate monohydrate.