Determination of amezinium in plasma by RP HPLC and its application to bioequivalence studies.

A modified method is described for the determination of 4-amino-6-methoxy-l-phenylpyridazinium methyl sulfate (amezinium metisulfate) in plasma and in the dosage form. The method involves a sample preparation using SPE and liquid-liquid extraction and subsequent determination by high performance liquid chromatography. Retention time for amezinium was 3.