Raloxifene

Application in Particular Diseases

In Osteoporosis:

• Raloxifene is an estrogen agonist on bone but an antagonist on the breast and uterus. It is approved for prevention and treatment of postmenopausal osteoporosis. Other estrogen agonists/antagonists may be approved soon (e.g., bazedoxifene, lasofoxifene).
• Raloxifene decreases vertebral fractures and increases spine and hip BMD, but to a lesser extent than bisphosphonates. After discontinuation, the beneficial effect is lost and bone loss returns to age- or disease-related rates.
• Raloxifene (like tamoxifen) is associated with decreased breast cancer risk. Raloxifene is associated with decreases in total and low-density lipoprotein cholesterol, neutral effects on high-density lipoprotein cholesterol, but slight increases in triglycerides; no beneficial cardiovascular effects have yet been demonstrated.
• Raloxifene is well tolerated overall. Hot flushes occur more frequently in women recently finishing menopause or discontinuing estrogen therapy (ET). Endometrial bleeding occurs rarely. Raloxifene is contraindicated in women with an active or past history of venous thromboembolism. Therapy should be stopped if a patient anticipates extended immobility.

Chemical Properties

Light-Yellow Solid

Uses

A nonsteroidal estrogen receptor mixed agonist/antagonist

Uses

Raloxifene is a nonsteroidal, selective estrogen receptor modulator (SERM). Antiosteoporotic.

Indications

Raloxifene (Evista) is a new SERM approved for use in the treatment and prevention of osteoporosis because it has estrogenic activity in bone. Raloxifene is an estrogen antagonist in both breast and endometrial tissues. The estrogenlike properties of raloxifene result in the maintenance of a favorable serum lipid profile (decreased low-density lipoprotein levels with no change in either high-density lipoproteins or triglycerides). Raloxifene is 95% bound to plasma proteins. Absorption of raloxifene is impaired by cholestyramine.

Definition

ChEBI: A member of the class of 1-benzothiophenes that is 1-benzothiophene in which the hydrogens at positions 2, 3, and 6 have been replaced by p-hydroxyphenyl, p-[2-(piperidin-1-yl)ethoxy]benzoyl, and hydroxy groups, respectively.

brand name

Evista (Lilly).

General Description

Raloxifene, [6-hydroxy-2-(4-hydroxyphenyl)benzo[b]thien-3-yl][4-[2-(1-piperidinyl)ethoxy]phenyl]methanone (Evista), is a benzothiophene derivativethat differs slightly from the triphenylethyleneSERMs. A key structural difference is the carbonyl “hinge”that connects the modified phenolic side chain to the benzothiophenering system. This hinge is the key structural elementthat leads to the differing actions at the ERs.Raloxifene, unlike tamoxifen and toremifene, has antagonistproperties on the endometrium and breast tissue and agonistproperties on bone and the cardiovascular system. The lackof agonist action on endometrial tissue has been suggestedas a reason for the lack of endometrial cancer associatedwith raloxifene use. Raloxifene is approved for the preventionand treatment of osteoporosis in postmenopausalwomen. It has also been investigated for preventing breastcancer in comparison with tamoxifen. Recent studies indicatesthat it has similar effectiveness to tamoxifen, but has apreferable side effect profile.

Biological Activity

Selective estrogen receptor modulator (SERM) that binds to ER α and ER β , and tissue-dependently activates or blocks estrogen-induced transcription. Acts as an antiestrogen in breast and uterine tissue, but displays estrogen agonist activity in bone. In D12 rat hypothalamic cells, inhibits progesterone receptor induction by estrogen with an IC 50 of 1 nM.

Clinical Use

Raloxifene, the first SERM approved for the prevention of osteoporosis in postmenopausal women, acts as an estrogen agonist on receptors in osteoblasts and osteoclasts but as an antagonist at breast and uterine estrogen receptors.