Understanding HRT and the Role of Progestogens
Hormone Replacement Therapy (HRT) is a treatment used to alleviate symptoms associated with menopause, such as hot flashes, night sweats, and mood swings [1.3.1]. This therapy works by replacing the hormones that the body stops producing during menopause, primarily estrogen [1.3.4]. For women who have a uterus, estrogen-only HRT can increase the risk of developing cancer of the womb lining (endometrial cancer) [1.6.1]. To counteract this risk, a progestogen is included in the treatment [1.6.1]. Dydrogesterone is one such progestogen, a synthetic hormone designed to mimic the effects of natural progesterone [1.3.5].
Femoston: The Primary HRT with Dydrogesterone
The most common HRT medication that contains dydrogesterone is sold under the brand name Femoston [1.2.3, 1.2.4]. It's a combination therapy that includes both an estrogen (estradiol) and the progestogen dydrogesterone [1.3.1]. Femoston is available in several formulations to cater to individual patient needs, with varying dosages of estradiol and dydrogesterone [1.2.4]. It is widely marketed throughout the world, although it is not available in the United States or Canada [1.2.4].
Femoston is prescribed for two main reasons:
- Relief of menopausal symptoms: It alleviates symptoms like hot flushes, night sweats, and mood swings in postmenopausal women [1.6.1].
- Prevention of osteoporosis: It helps prevent the thinning of bones that can occur after menopause, reducing the risk of fractures [1.6.1].
There are different types of Femoston, which allow for either sequential or continuous combined therapy. For example, Femoston 1/10 and 2/10 are sequential therapies, where the estrogen is taken daily and the dydrogesterone is added for part of the cycle, often leading to a withdrawal bleed [1.3.7]. Femoston-conti provides a continuous dose of both hormones, which is intended for women who have not had a period for at least 12 months and typically does not cause a monthly bleed [1.6.1, 1.6.3].
What is Dydrogesterone?
Dydrogesterone is an orally active synthetic progestogen with a molecular structure very similar to natural progesterone [1.4.7]. Unlike some other synthetic progestogens (progestins), it has a favorable profile because it is highly selective for progesterone receptors and does not interfere with the beneficial effects of estrogen on things like cardiovascular health [1.4.3, 1.4.6]. It effectively protects the endometrium from hyperplasia (excessive thickening) that can be caused by estrogen [1.4.2]. Some studies suggest that its combination with estradiol does not increase the risk of venous thromboembolism or breast cancer compared to other combined HRT regimens, and it maintains a neutral effect on metabolic systems [1.4.3, 1.4.5]. It is considered a safe option for luteal support during pregnancy under medical guidance [1.8.2].
Comparison of Dydrogesterone with Other Progestogens
Choosing an HRT regimen involves considering the specific type of progestogen included. Each has a different profile regarding side effects and health risks.
| Feature | Dydrogesterone | Micronized Progesterone | Norethisterone |
|---|---|---|---|
| Type | Synthetic (retroprogesterone) [1.4.3] | Bioidentical [1.7.3] | Synthetic Progestin |
| Administration | Oral, with good bioavailability [1.5.3] | Oral or Vaginal [1.5.4] | Oral, Transdermal [1.2.2] |
| Cardiovascular Impact | Considered to have a neutral or favorable effect [1.4.5, 1.4.6] | Generally considered neutral | Can have a less favorable impact on cholesterol [1.8.5] |
| Common Side Effects | Headache, nausea, breast tenderness [1.8.3] | Drowsiness (often taken at night to aid sleep) [1.7.3] | Mood swings, bloating, acne [1.8.5] |
| Breast Cancer Risk | Some studies suggest no increased risk compared to other HRTs [1.4.3, 1.4.5] | Considered to have a lower risk compared to many synthetic progestins [1.7.3] | Associated with a small increased risk in long-term HRT use |
Potential Side Effects and Considerations
Like all medications, HRT containing dydrogesterone carries potential risks and side effects. It is crucial to have regular check-ups with a doctor to discuss the benefits and risks [1.6.1].
Common side effects of Femoston can include [1.6.4]:
- Headache
- Abdominal pain
- Back pain
- Breast tenderness
- Feeling sick (nausea)
- Irregular bleeding or spotting, especially in the first 3-6 months [1.6.1]
Serious risks associated with HRT in general include a slightly increased risk of [1.6.4]:
- Blood clots (venous thromboembolism)
- Stroke
- Breast cancer (the risk depends on the type and duration of HRT)
- Ovarian cancer
HRT containing dydrogesterone should not be used by individuals with a history of breast cancer, estrogen-sensitive cancers, unexplained vaginal bleeding, untreated endometrial hyperplasia, or active blood clots [1.6.1]. It is essential to provide a full medical history to your doctor before starting any HRT.
Conclusion
The primary HRT medication that contains dydrogesterone is Femoston, which combines it with estradiol. Dydrogesterone is a synthetic progestogen valued for its safety profile, including its neutral effects on metabolic and vascular systems, while effectively protecting the uterus lining [1.4.3, 1.4.5]. It offers a valuable option for women seeking relief from menopausal symptoms and prevention of osteoporosis. As with any medical treatment, the decision to use a dydrogesterone-containing HRT should be made in consultation with a healthcare provider after a thorough evaluation of individual health risks and benefits.
For more detailed information, you can consult the patient information leaflet for Femoston-conti provided by the electronic Medicines Compendium.
