Cerebral and blood pharmacokinetics of imipramine and its active metabolites in the pregnant rat

Abstract
A single IP dose of imipramine (IMI) was administered to pregnant rats. Whole blood, plasma, and brain concentrations of IMI, desipramine (DMI), and their 2-hydroxylated metabolites were separated by high-pressure liquid chromatography and quantified by fluorescence detection. IMI and DMI rapidly appeared in brain tissue in concentrations greatly exceeding those in whole blood and plasma. The much higher concentration and longer persistence of DMI in brain compared to IMI suggests that the predominant central effects from administered IMI result from biotransformation to DMI. The metabolite: “parent” area under the curve ratios for the hydroxylated metabolites indicate that their contribution to the pharmacologic effects of IMI and DMI are probably negligible.