Publication Cover
Xenobiotica
the fate of foreign compounds in biological systems
Volume 20, 1990 - Issue 1
12
Views
8
CrossRef citations to date
0
Altmetric
Original Article

The metabolism of 2,4-dibromo-17α-ethynyl[6,7-3H]oestradiol in the rat

, , , &
Pages 45-54 | Received 21 Mar 1989, Accepted 18 Aug 1989, Published online: 27 Aug 2009
 

Abstract

1. The metabolism of 2,4-dibromoethynyloestradiol (2,4-DBEE2) in the rat was studied in order to determine the influence of ring-A substituents on the phase I biotransformations of oestrogens.

2. 2,4-Dibromo-17α-ethynyl[6,7-3H]oestradiol was synthesized by the one-stage bromination of 17α-ethynyl[6,7-3H]oestradiol (EE2) with N-bromoacetamide, and administered (30 μg/kg, i.v.) to anaesthetized male and female rats.

3. A single metabolite, identified as a glucuronide of 2,4-DBEE2, was rapidly and extensively eliminated in bile by male rats (83% of the dose over 6 h). Females excreted additional minor conjugated metabolites. Neither unchanged 2,4-DBEE2 nor EE2 was detected in bile.

4. The hepatic residues after 6 h (percentage of dose) were 2.7% and 3.4% in male and female rats, respectively, whilst <0.1% per organ(s) was found in kidneys, heart, spleen, lungs and brain.

5. 2,4-Dibromo substitution of EE2 effectively blocked all phase I biotransformations whilst not limiting glucuronylation in male rats, but did not entirely preclude phase I metabolism in females. The inertness of 2,4-DBEE2 to ring-A hydroxylation in male rats conforms with the insignificant debromination of 2,4-dibromoestradiol by hepatic microsomes.

Reprints and Corporate Permissions

Please note: Selecting permissions does not provide access to the full text of the article, please see our help page How do I view content?

To request a reprint or corporate permissions for this article, please click on the relevant link below:

Academic Permissions

Please note: Selecting permissions does not provide access to the full text of the article, please see our help page How do I view content?

Obtain permissions instantly via Rightslink by clicking on the button below:

If you are unable to obtain permissions via Rightslink, please complete and submit this Permissions form. For more information, please visit our Permissions help page.