1. Clinical Overview
Raloxifene is a second-generation selective estrogen receptor modulator (SERM) used primarily for the prevention and treatment of postmenopausal osteoporosis. It acts as an estrogen agonist on bone and lipid metabolism while acting as an estrogen antagonist on breast and uterine tissue. It is a non-hormonal, oral therapy that reduces the risk of vertebral fractures.
| Onset | Duration | Bioavailability |
|---|---|---|
| Biochemical markers of bone resorption (e.g., serum C-telopeptide) decrease within weeks, but significant anti-fracture efficacy is observed after 6-12 months of continuous therapy. | The therapeutic effect on bone mineral density (BMD) is sustained with continued daily dosing. Effects on fracture risk reduction persist as long as treatment is continued. | Approximately 2% due to extensive first-pass glucuronide conjugation. |
2. Mechanism of Action
Raloxifene binds to estrogen receptors (ER) with high affinity, resulting in differential expression of estrogen-regulated genes in various tissues. It acts as an estrogen agonist in bone (increasing mineralization, reducing resorption) and on lipid metabolism (decreasing LDL cholesterol). It acts as an estrogen antagonist in breast and uterine tissue, blocking the proliferative effects of estrogen.
3. Indications & Uses
- Prevention of osteoporosis in postmenopausal women
- Treatment of osteoporosis in postmenopausal women to reduce the risk of vertebral fractures
4. Dosage & Administration
Adult Dosage: 60 mg orally once daily, with or without food.
Administration: Tablet should be swallowed whole with a glass of water. Can be taken at any time of the day, with or without food. If a dose is missed, it should be taken as soon as remembered on the same day. Two tablets should not be taken on the same day. Calcium (1000-1500 mg/day) and Vitamin D (400-800 IU/day) supplementation is recommended unless contraindicated.
5. Side Effects
Common side effects may include:
- Hot flushes (vasodilation)
- Leg cramps
- Peripheral edema
- Flu-like syndrome
- Arthralgia
- Sweating
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Warfarin | Raloxifene may modestly decrease prothrombin time. Monitor INR closely when starting or stopping raloxifene. | Moderate |
| Cholestyramine | Significantly reduces the absorption and enterohepatic cycling of raloxifene by ~60%. Administer at least 2 hours before or 4-6 hours after cholestyramine. | Major |
| Ampicillin, Amoxicillin | May reduce enteric hydrolysis of raloxifene glucuronides, potentially decreasing enterohepatic cycling and efficacy. | Moderate |
| Systemic Estrogens (Oral, Transdermal) | Concomitant use is not recommended. May interfere with the SERM activity and safety profile. | Major |
7. Patient Counselling
- DO take the tablet once daily, with or without food.
- DO take supplemental calcium and vitamin D as advised by your doctor.
- DO report any unexplained leg pain, swelling, chest pain, or shortness of breath immediately.
- DO inform all your doctors and surgeons that you are taking raloxifene, especially before any surgery or period of prolonged immobilization.
- DONT take the medicine if you are pregnant, planning pregnancy, or breastfeeding.
- DONT take cholestyramine or colestipol at the same time; separate doses by several hours.
8. Toxicology & Storage
Overdose: Limited data. In clinical trials, doses up to 600 mg/day have been administered. Expected symptoms may include leg cramps, dizziness, rash, and flushing. There is no experience with single doses > 600 mg.
Storage: Store below 30°C. Protect from light and moisture. Keep the tablet in the blister pack until use. Keep out of reach of children.