Disposition and metabolism of indeloxazine hydrochloride,a cerebral activator,in rats

1. The disposition and metabolism of indeloxazine hydrochloride ((±) -2-(inden-7-yloxy)methyl]morpholine hydrochloride) were studied in male Sprague-Dawley rats.

2. After oral administration of ¹⁴C-indeloxazine hydrochloride, the plasma concentration of total radioactivity reached a maximum at 15 min and declined with an apparent half-life of 2.2h in the first 6h period and declined more slowly thereafter. Unchanged drug in the plasma represented 13.5%, 5.9% and 0.4% of the total radioactivity at 15 min, 1 h and 6 h respectively after administration and levels decayed with a half-life of 0.9 h.

3. After oral and i.v. administration of the labelled compound, the urinary and faecal excretion of radioactivity in 72 h were 61–65% and 31–36% of the dose, respectively. Biliary excretion in bile duct-cannulated animals amounted to 49% of the dose in 72 h.

4. Seven metabolites have been isolated from the plasma or urine and characterized by i.r., n.m.r. and mass spectrometry. They were derived through dihydrodiol formation in the indene ring, hydroxylation of the indene ring and N-acetylation, oxidation and oxidative degradation of the morpholine ring. Some metabolites were excreted as their glucuronic acid or glucose conjugates. The major metabolite appcared to the trans-indandiol analogue of indeloxazine.

5. Possible metabolic pathways of degradation of the morpholine ring are discussed.