1978 Volume 26 Issue 7 Pages 2241-2246
Spectrofluorometric assay for the quantitative determination of ecarazine hydrochloride (I) and its metabolite, 3-methyl-s-triazolo (3, 4-a) phthalazine (III) were described. I and III were extracted from plasma at weakly alkaline pH with chloroform and fluorescence of III was directly measured (Ex 250, Em 410 nm). The chloroform layer containing I was treated with alkali at elevated temperature to give s-triazolo (3, 4-a) phthalazine-2H-3-one (II). The fluorescence of II was measured at an emission wavelength 470 and excitation of 266 nm. There was a linear relationship between concentration of I and fluorometric response up to 10μg/ml in plasma. This assay was sensitive enough to be useful for the determination of I and III and had a sensitivity limit of 0.2 and 0.07μg/ml, respectively. Other antihypertensive agents and some metabolites had no detectable effect on the present assay. The method was applied to the determination of plasma levels in rats and dogs after oral or intravenous administration (3 or 10 mg/kg) of I.
