Comparison of observed and predicted first-pass metabolism of imipramine in humans.

The first-pass metabolism of imipramine was calculated based on the dose, hepatic blood flow, and total area under the plasma-time curve after oral administration of 0.71 +/- 0.03 mg/kg of imipramine to four individuals suffering from mild depression. The predicted values of first-pass metabolism ranged from 37 to 68%, consistent with experimentally derived estimates.