Studies on the Metabolism of the New Anti-Hypertensive Agent, Indoramin, in Man

The absorption, metabolism and excretion of the new antihypertensive agent indoramin (Baratol®) have been studied in male volunteers following oral administration of the drug labelled either with 14C or with tritium. Absorption of the drug proceeded at moderate rate, peak plasma radioactivity levels being seen by 3 h after dosing. Metabolism was extensive as shown by very little unchanged compound appearing in urine. Two major urinary metabolites accounting for some 35–40% of the renally excreted material were identified as acid labile conjugates of indoramin itself and indole 6-hydroxylated indoramin. The pattern of biotransformation appeared to be similar to that in the patas monkey, the species used in the long term safety evaluation of the drug. Excretion of the drug and metabolites occurred primarily via the faeces which accounted for 49.7±4.9% of the dose. A further 31.7±2.4% was recovered in the urine. Renal elimination of total radioactivity occurred in an apparently monoexponential manner with a half-life of 11.9±1.2 h.