Bazedoxifene: A Third-Generation Selective Estrogen Receptor Modulator for Treatment of Postmenopausal Osteoporosis

Abstract

To review clinical studies and other available literature regarding the development, pharmacology, toxicology, pharmacokinetics/pharmacodynamics, adverse effects, and place in therapy of bazedoxifene, a selective estrogen receptor modulator (SERM), currently in Phase III clinical trials for the treatment and prevention of postmenopausal osteoporosis. A literature search was performed of PubMed (1966-February 2007), International Pharmaceutical Abstracts (1970-February 2007), Web of Science (1975-February 2007), Biological Abstracts (1926-2007), and Google Scholar (2001-February 2007) databases, using the search terms bazedoxifene, TSE-424, Indole-33, WAY-140424, selective estrogen receptor modulator, and SERM. In addition, product information was requested from the manufacturer, and www.clinicaltrials.gov was searched for unpublished Phase III clinical trials in progress. Articles on Phase I and II trials were selected for review, as well as articles discussing preclinical development of bazedoxifene. At the time of writing, no articles on Phase III trials were available for review. Abstracts of unpublished data were reviewed, as was information provided by the manufacturer. Bazedoxifene is a third-generation SERM currently in Phase III clinical trials. It has been found to act as an agonist on skeletal tissue, with bone turnover reduced by 20-25% with doses of 20 or 40 mg daily. In addition, bazedoxifene has been found to be an antagonist on breast tissue and uterine tissue, demonstrating inhibition of breast tissue proliferation and decreased endometrial stimulation as the dose is increased. Current literature suggests that bazedoxifene will likely be safe and effective when used in the treatment of postmenopausal osteoporosis. Completion of Phase III clinical trials will more fully elucidate the safety and efficacy profile of bazedoxifene, as well as more clearly define its place in therapy.