Km: 75 μM

Estradiol 17-(β-D-Glucuronide) is a substrate of the multidrug resistance protein 2 (MRP2).

MRP2 is a member of the superfamily of ATP-binding cassette (ABC) transporters, which transport various molecules across extra- and intra-cellular membranes. MRP2 is a member of the MRP subfamily that is involved in multi-drug resistance. MRP2 is expressed in the apical side of the hepatocyte and functions in biliary transport.

In vitro: Estradiol 17-(β-D-Glucuronide) was identified as an ATP dependent, osmotically sensitive transport of the naturally occurring conjugated estrogen, and was found to be readily demonstrable in plasma membrane vesicles from populations of MRP-transfected HeLa cells. The involvement of MRP was confirmed by demonstrating that transport was completely inhibited by a monoclonal antibody specific for an intracellular conformational epitope of the protein [1].

In vivo: Animal study found that estradiol 17-(β-D-Glucuronide) could induce an immediate, profound and reversible inhibition of bile flow after its i.v. administration to the rat. Moreover, the cholestasis degree was found to be dose-dependent in the range of 8.5 to 21 mumol/kg i.v. A dose of 11 mumol/kg i.v. was able to inhibit bile flow and bile acid secretory rate 65 to 70% within 15 to 30 min of its administration. In addition, the bile flow and bile acid secretion returned to near control levels within 3 hours [2].

Clinical trial: So far, no clinical study has been conducted.

References:
[1] Loe, D.?W.,Almquist, K.C.,Cole, S.P., et al. ATP-dependent 17β-estradiol 17-(β-D-glucuronide) transport by multidrug resistance protein (MRP). Inhibition by cholestatic steroids. The Journal of Biological Chemisty 271(16), 9683-9689 (1996).
[2] Meyers M, Slikker W, Pascoe G, Vore M.? Characterization of cholestasis induced by estradiol-17 beta-D-glucuronide in the rat. J Pharmacol Exp Ther. 1980 Jul;214(1):87-93.