Overview
Tibolone is a synthetic steroid with estrogenic, progestogenic, and weak androgenic properties used primarily for managing menopausal symptoms and preventing osteoporosis in postmenopausal women. It acts as a tissue-selective hormone, producing different effects in various tissues.
Mechanism of Action
Tibolone and its metabolites (3α-OH-tibolone, 3β-OH-tibolone, and Δ4-isomer) act as tissue-selective hormone regulators. The 3α/β-OH metabolites exert estrogenic effects on bone, brain, and vagina, while the Δ4-isomer has progestogenic and androgenic activity. This selective action provides estrogen-like benefits on bone and menopausal symptoms while minimizing endometrial stimulation.
Indications
- Treatment of vasomotor symptoms (hot flashes, night sweats) associated with menopause
- Prevention of osteoporosis in postmenopausal women at high risk of fractures
Dosage
2.5 mg orally once daily. Treatment should be initiated within 12 months after last menstrual period or after confirmed postmenopausal status. Continuous administration without cyclic breaks.
Contraindications
- Known or suspected pregnancy
- Undiagnosed abnormal genital bleeding
- Known, suspected, or history of breast cancer
- Known or suspected estrogen-dependent neoplasia
- Active or history of arterial thromboembolic disease
- Active or recent venous thromboembolism
- Severe hepatic dysfunction
- Hypersensitivity to tibolone or any component
Side Effects
- Headache
- Abdominal pain
- Breast pain
- Vaginal bleeding/spotting
- Weight changes
- Dizziness
- Nausea
- Edema
- Skin reactions (rash, pruritus)
- Mood changes
- Increased facial hair growth
- Voice changes
Interactions
- Enzyme-inducing drugs (carbamazepine, phenytoin, rifampicin) - may reduce tibolone efficacy
- Anticoagulants (warfarin) - may alter anticoagulant effect
- Herbal supplements with estrogenic activity (black cohosh, soy isoflavones)