Bazedoxifene

Absorption

Bazedoxifene is rapidly absorbed with a tmax of approximately 2 hours and exhibits a linear increase in plasma concentrations for single doses from 0.5 mg up to 120 mg and multiple daily doses from 1 mg to 80 mg. The absolute bioavailability of bazedoxifene is approximately 6%.

The Uses of Bazedoxifene

Bazedoxifene is an nonsteroidal selective estrogen receptor modulator (SERM). Bazedoxifene is used as an antiosteoporotic.

Background

Bazedoxifene is a third generation selective estrogen receptor modulator (SERM), developed by Pfizer following the completion of their takeover of Wyeth Pharmaceuticals. In late 2013, Pfizer received approval for bazedoxifene as part of the combination drug DUAVEE in the prevention (not treatment) of postmenopausal osteoporosis. It is approved in the European Union (marketed in Italy and Spain) and Japan as monotherapy. In 2013, the combination product containing conjugated estrogens and bazedoxifene was approved by the FDA for the treatment of moderate to severe vasomotor symptoms associated with menopause, as well as the prevention of postmenopausal osteoporosis in women.

Indications

Indicated for following conditions alone or in combination with conjugated estrogens in women with a uterus:

Definition

ChEBI: Bazedoxifene is a phenylindole.

General Description

Bazedoxifene, 1-[[4-[2-(azepan-1-yl)ethoxy]phenyl]methyl]-2-(4-hydroxyphenyl)-3-methylindol-5-ol (Viviant), was declared to be “approvable” bythe FDA in 2007 for the prevention of postmenopausalosteoporosis. As of mid-2009, final approval in the UnitedStates is still pending. Bazedoxifene was approved inEurope in 2009 for the treatment of post–menopausalosteoporosis.

Clinical Use

Bazedoxifene is an indole-based SERM that is under investigation for the treatment and prevention of postmenopausal osteoporosis. It also is being evaluated in combination with Premarin (conjugated estrogens). Bazedoxifene displaces 17β-estradiol from estrogen receptors and has excellent binding affinity for the receptor itself. Unlike raloxifene, this agent does not cause hot flashes at the doses required to have a beneficial effect on bone. In addition, it does not cause uterine or mammary gland stimulation.

Enzyme inhibitor

This potent and selective estrogen receptor modulator, or SERM (FW = 530.65 g/mol; CAS 198481-33-3; Solubility: 00 mM in DMSO), also named 1-[[4-[2- (hexahydro-1H-azepin-1-yl) ethoxy]phenyl]methyl]-2- (4- hydroxyphenyl) -3-methyl-1H-indol-5-ol, selectivity targets the extrogen receptor ERα (IC50 = 26 nM), with weaker action against ERβ (IC50 = 99 nM), inhibiting 17β-estradiol-induced proliferation of MCF-7 cells. Bazedoxifene represents a promising new treatment for osteoporosis, one with a potential for less uterine and vasomotor effects than selective estrogen receptor modulators now used clinically.

Metabolism

Glucuronidation is the major metabolic pathway. After peroral application, bazedoxifene is metabolized by UDP-glucuronosyltransferases (UGTs) to bazedoxifene-4'-glucuronide (M4) and bazedoxifene-5-glucuronide (M5).Little or no cytochrome P450-mediated metabolism is evident. The concentrations of this glucuronide are approximately 10-fold higher than those of unchanged active substance in plasma.