Registered South Africa · SAHPRA

FEMOSTON 1/10

DYDROGESTERONE , ESTRADIOL

36/21.8.2/0329 genito urinary system and sex hormones INN generic

What it does

Dydrogesterone is a synthetic hormone similar to progesterone, used to support various reproductive health issues.

Commonly used for: irregular menstrual periods, endometriosis, hormone replacement therapy

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Plain-language summary for general understanding - not medical advice. Always follow your pharmacist/doctor.

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Registration & product details

Registration no.
36/21.8.2/0329
Registration date
2003/05/09
Expiry date
-
Status
Registered
Active ingredient
DYDROGESTERONE , ESTRADIOL
Dosage form
-
Strength
-
Pack size
-
Therapeutic class
-
ATC class (WHO)
G03DB - Pregnadien derivatives
RxNorm RxCUI
3706
Manufacturer / MAH
-
Country of origin
-

Source: South African Health Products Regulatory Authority · fetched 2026-04-15 21:11:23 · updated 2026-09-16 04:00:04

Drug Interactions

6
Check interactions

Unknown (6)

Estradiol - decreases efficacy

Antiepileptics (carbamazepine, eslicarbazepine, fosphenytoin, oxcarbazepine, perampanel, phenobarbital, phenytoin, primidone, rufinamide, topiramate) are predicted to decrease the efficacy of estradio

Unknown Theoretical

Estradiol - decreases efficacy

Bosentanispredictedtodecreasetheefficacyofestradiol. oTheoretical

Unknown Theoretical

Estradiol - decreases efficacy

Modafinilispredictedtodecreasetheefficacyofestradiol. oTheoretical

Unknown Theoretical

Estradiol - decreases efficacy

Rifamycinsarepredictedtodecreasetheefficacyofestradiol. oTheoretical

Unknown Theoretical

Estradiol - decreases efficacy

StJohn’swortispredictedtodecreasetheefficacyofestradiol. oTheoretical Estramustine→seealkylatingagents Etanercept

Unknown Theoretical

Estradiol - decreases efficacy

Ritonavirispredictedtodecreasetheefficacyofestradiol. oTheoretical

Unknown Theoretical

Data from BNF 85 (British National Formulary). This is not a substitute for professional medical advice. Matched via: exact

Disclaimer: This information is sourced from South African Health Products Regulatory Authority (South Africa). Always consult a qualified healthcare professional before using any medication.

About dydrogesterone

Dydrogesterone is a synthetic hormone similar to progesterone, used to support various reproductive health issues.

What it treats

  • irregular menstrual periods
  • endometriosis
  • hormone replacement therapy

How it works

Dydrogesterone helps to regulate the menstrual cycle and supports pregnancy by balancing hormones in the body.

Who it's for

This medication is suitable for women experiencing hormonal imbalances related to their menstrual cycle or pregnancy.

AI-assisted summary grounded in BNF data - general information only, not medical advice. Always confirm with your pharmacist or doctor.

About estradiol

Estradiol is a form of estrogen, a female hormone important for various body functions.

What it treats

  • menopausal symptoms
  • hormone replacement therapy
  • female hypogonadism
  • certain types of breast cancer

How it works

Estradiol helps to balance hormone levels in the body, relieving symptoms associated with low estrogen.

Who it's for

This medication is for women experiencing menopause or hormonal imbalances.

AI-assisted summary grounded in BNF data - general information only, not medical advice. Always confirm with your pharmacist or doctor.

Clinical monograph: dydrogesterone

BNF-referenced

Dydrogesterone is a synthetic progestogen, which mimics the effects of the natural hormone progesterone. It plays a crucial role in regulating the menstrual cycle, preparing the uterus for implantation, and maintaining pregnancy. Dydrogesterone is particularly effective in the treatment of various menstrual disorders and is known for its non-androgenic and non-estrogenic properties, making it a suitable option for women who require progestogen therapy without the side effects associated with other hormonal treatments.

Indications

  • Amenorrhea
  • Irregular menstrual periods
  • Dysmenorrhea
  • Infertility
  • Premenstrual syndrome
  • Endometriosis

Dosage

Adults: The typical dosage for adults is 10 mg taken orally, three times a day, from day 5 to day 25

Mechanism of action

Dydrogesterone acts on progesterone receptors in the uterus, regulating the healthy growth and normal shedding of the womb lining. By doing so, it reduces the risk of endometrial hyperplasia and cancer in non-hysterectomised women. Its action helps create a complete secretory endometrium in an estrogen-primed uterus, without affecting ovulation or corpus luteum function.

Pharmacodynamics

As an orally active progestogen, dydrogesterone does not exhibit contraceptive effects at therapeutic levels, as it does not inhibit ovulation. It is characterized by its non-androgenic, non-estrogenic, and non-corticoid properties, making it distinct from other progestins. Dydrogesterone is effective in treating menstrual disorders, including absent, irregular, or painful menstrual periods, infertility, premenstrual syndrome, and endometriosis. Its unique profile supports its therapeutic use in conditions where progesterone is lacking or needs to be supplemented.

Pharmacokinetics

Dydrogesterone is well absorbed after oral administration, with peak plasma concentrations occurring within 1 to 3 hours. It has a half-life of approximately 5 to 7 hours, allowing for convenient dosing schedules. The drug is metabolized primarily in the liver and is excreted mainly via urine, with a minimal percentage eliminated unchanged. Its pharmacokinetic properties support its use as a safe and effective treatment option for various menstrual and reproductive health issues.

Contra-indications

  • Known hypersensitivity to dydrogesterone or any excipients
  • Active liver disease
  • History of hormone-dependent malignancies, such as breast cancer
  • Undiagnosed vaginal bleeding
  • Thromboembolic disorders

Adverse effects

  • Headache
  • Nausea
  • Breast tenderness
  • Mood changes
  • Weight gain
  • Abdominal pain
  • Dizziness
  • Menstrual irregularities

Interactions

  • Anticonvulsants may decrease the effectiveness of dydrogesterone
  • Rifampicin may reduce plasma concentrations of dydrogesterone
  • St. John's Wort may reduce the efficacy of dydrogesterone
  • CYP3A4 inducers may affect dydrogesterone metabolism

Precautions

  • Monitor for signs of thromboembolic events in patients with a history of such conditions
  • Use with caution in patients with cardiovascular disease
  • Consider the risk of endometrial hyperplasia in women with irregular menstruation
  • Evaluate the benefits versus risks in patients with liver impairment

Pregnancy

Dydrogesterone is used during pregnancy to support the luteal phase and prevent miscarriage in women with progesterone deficiency. It should be prescribed cautiously and under medical supervision.

Breast-feeding

Dydrogesterone is considered safe during breastfeeding, but monitoring for any possible effects on the infant is advised.

Storage

Store at room temperature, away from moisture and heat. Keep out of reach of children.

Formulations

  • Oral tablets

AI-synthesized from BNF references - general information only, not a substitute for professional medical advice or the current BNF. Verify doses with a pharmacist.

Clinical monograph: Estradiol

BNF-referenced

Estradiol is a potent estrogen hormone predominantly produced by the ovarian follicles in premenopausal women. Following menopause, estradiol is primarily synthesized from androstenedione in peripheral tissues. It plays a critical role in regulating various physiological processes, including reproductive function, bone density, and cardiovascular health. Estradiol is utilized in hormone replacement therapy (HRT) to alleviate menopausal symptoms and prevent osteoporosis in postmenopausal women.

Indications

  • Menopausal symptoms
  • Osteoporosis prophylaxis
  • Irregular menstruation
  • Vulvovaginal atrophy
  • Postmenopausal urogenital conditions

Dosage

Adults: The typical adult dosage of estradiol is 2 mg daily, initiated on day 1-5 of the menstrual cycle or at any time if cycles have ceased or are infrequent, taken with

Mechanism of action

Estradiol exerts its effects by binding to estrogen receptors, specifically estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ), as well as the G protein-coupled estrogen receptor (GPER). This binding triggers the receptor-ligand complex to translocate to the nucleus, where it regulates gene transcription and the synthesis of specific proteins that mediate estradiol's physiological effects.

Pharmacodynamics

Estradiol acts on estrogen receptors to alleviate vasomotor symptoms such as hot flashes and urogenital symptoms including vaginal dryness. It has beneficial effects on bone density by inhibiting bone resorption and improving plasma lipid profiles. Additionally, estradiol decreases follicle-stimulating hormone (FSH) levels by suppressing its formation in the anterior pituitary gland. Notably, it may increase the risk of cardiovascular events, venous thromboembolism, and stroke, necessitating caution in high-risk populations.

Pharmacokinetics

Estradiol is rapidly absorbed when administered orally, with a bioavailability affected by first-pass metabolism in the liver. It is extensively metabolized in the liver, conjugated to form estrone and estrone sulfate, and eliminated through urine. The half-life of estradiol varies depending on the route of administration, with peak plasma concentrations occurring within 1-3 hours post-administration. Continuous use can lead to accumulation and requires careful monitoring of therapy duration and dosage adjustments.

Contra-indications

  • History of thromboembolic disorders
  • Known or suspected estrogen-dependent tumors
  • Undiagnosed abnormal genital bleeding
  • Severe liver dysfunction
  • Pregnancy

Adverse effects

  • Nausea
  • Headaches
  • Weight changes
  • Breast tenderness
  • Mood alterations
  • Vaginal discharge
  • Oedema
  • Skin reactions
  • Thromboembolic events
  • Cerebrovascular accidents
  • Endometrial hyperplasia
  • Angioedema

Interactions

  • Antiepileptics (carbamazepine, phenytoin, etc.) may decrease efficacy of estradiol
  • Bosentan may decrease efficacy of estradiol
  • Modafinil may decrease efficacy of estradiol
  • Rifamycins may decrease efficacy of estradiol
  • St. John's Wort may decrease efficacy of estradiol
  • Ritonavir may decrease efficacy of estradiol

Precautions

  • Monitor for signs of thromboembolic events
  • Evaluate for endometrial hyperplasia in women with a uterus
  • Consider cardiovascular risks before initiating therapy
  • Assess liver function prior to use
  • Use with caution in patients with a history of depression

Pregnancy

Estradiol is contraindicated in pregnancy due to potential harm to the fetus and increased risk of thromboembolic events.

Breast-feeding

Estradiol is excreted in breast milk; caution is advised when used by nursing mothers as it may affect milk production.

Storage

Store in a cool, dry place away from direct sunlight. Keep out of reach of children.

Formulations

  • Tablets (1 mg, 2 mg)
  • Vaginal ring (continuous use, replaced every 3 months)
BNF 85 (British National Formulary) p.846 BNF 85 (British National Formulary) p.930 PubChem / pathway

AI-synthesized from BNF references - general information only, not a substitute for professional medical advice or the current BNF. Verify doses with a pharmacist.

Molecular reference: dydrogesterone

PubChem CID 9051

Molecular formula: C21H28O2

Mechanism of action

Dydrogesterone is a progestogen that works by regulating the healthy growth and normal shedding of the womb lining by acting on progesterone receptors in the uterus. Dydrogesterone is an orally-active progestagen. The addition of a progestagen greatly reduces the estrogen-induced risk of endometrial hyperplasia and cancer in non-hysterectomised women, by reducing the growth of the endometrium. Progestins cannot be equated as group with progesterone because some are inherently estrogenic, some slightly androgenic, and some purely progestational; correspondingly, their ovulation-inhibiting potentialities may be mediated in somewhat different ways. /Progestins/ The 17-hydroxy or acetoxy compounds, on the other hand, elicit responses more nearly resembling those of progesterone. They have little or no estrogenic or androgenic activity and may produce catabolic and slight diuretic effects. The 19-nor derivatives are more effective in postponing the normal menstrual period. /Progestins/ Accumulating evidence indicates that the neuropeptide substance P (SP) is predominantly involved in neurogenic inflammation and pain perception via its high-affinity neurokinin 1 receptor (NK-1R). Intriguingly, decreased pain sensitivity is found to be associated with high plasma progesterone levels. We hypothesize that progesterone may attenuate nociception and associated inflammatory response via NK-1R-dependent pathways. To address our hypothesis, we incubated splenic lymphocytes from CBA/J female mice with different concentrations of the progesterone derivative dydrogesterone. Subsequently, the expressions of NK-1R and T helper (Th1)-type cytokines were analyzed by flow cytometry. Next, we subcutaneously injected CBA/J mice with 1.25 mg of dydrogesterone in 200-microl sesame oil; control mice were sham-injected. Tail flick test to detect the nociceptive threshold was performed in 30-min intervals upon injection. Lymphocytes were isolated from blood and uterus and analyzed for NK-1R surface expression. Immunohistochemical analyses were performed to investigate the uterine tissue distribution of NK-1R. Dydrogesterone induced a decrease in the percentage of NK-1R+ lymphocytes in vitro and in vivo. Additionally, an increase in Th2-type and a decrease in Th1-type cytokines could be detected in vitro after incubation with dydrogesterone. An increased tail flick latency following dydrogesterone injection supported the concept that decreased expression of the NK-1R on lymphocytes is associated with an increased pain threshold. Taken together, these results clearly reveal a pathway by which dydrogesterone or progesterone respectively modulates the cross talk of the nervous, endocrine and immune systems in inflammation and pain. For more Mechanism of Action (Complete) data for DYDROGESTERONE (6 total), please visit the HSDB record page.

Pharmacodynamics

Dydrogesterone is an orally active progestogen which acts directly on the uterus, producing a complete secretory endometrium in an estrogen-primed uterus. At therapeutic levels, dydrogesterone has no contraceptive effect as it does not inhibit or interfere with ovulation or the corpus luteum. Furthermore, dydrogesterone is non-androgenic, non-estrogenic, non-corticoid, non-anabolic and is not excreted as pregnanediol. Dydrogesterone helps to regulate the healthy growth and normal shedding of the uterus lining. Therefore, it may be useful in the treatment of menstrual disorders such as absent, irregular or painful menstrual periods, infertility, premenstrual syndrome and endometriosis.

Source: PubChem (NCBI) · pathways from PathBank, Reactome, WikiPathways & PharmGKB.

Molecular reference: Estradiol

PubChem CID 5757

Molecular formula: C18H24O2

Mechanism of action

Estrogen is found in the the breast, uterine, ovarian, skin, prostate, bone, fat, and brain tissues. The main source of estrogen in adult women during the reproductive period of life is the ovarian follicle, which secretes 70 to 500 mcg of estradiol each day. After menopause, however, the majority of endogenous estrogen is produced by transformation of androstenedione (which is secreted by the adrenal cortex) to estrone in the peripheral tissues. Both estrone and its sulphate conjugated form, estrone sulphate, represent the most abundant estrogens found in postmenopausal women. Estradiol, however, is considerably more potent than estrone and estriol at the estrogen receptor (ER). As a result, the higher estrone concentration in postmenopausal population, can cause various undesirable effects. These effects may include hot flashes, chills, vaginal dryness, mood swings, irregular menstruation, and chills, in addition to sleep problems. Estradiol workings by binding to subtypes of the estrogen receptor: estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ). It also exerts potent agonism of G Protein-coupled estrogen receptor (GPER), which is recognized an important regulator of this drug's rapid effects. Once the estrogen receptor has bound to its ligand, it enters the nucleus of the target cell, regulating gene transcription and formation of of messenger RNA. This mRNA makes contact with ribosomes producing specific proteins that express the effect of estradiol upon the target cell. Agonism of estrogen receptors increases pro-estrogenic effects, leading to the relief of vasomotor and urogenital symptoms of a postmenopausal or low estradiol state. Endogenous estrogens are largely responsible for the development and maintenance of the female reproductive system and secondary sexual characteristics. Although circulating estrogens exist in a dynamic equilibrium of metabolic interconversions, estradiol is the principal intracellular human estrogen and is substantially more potent than its metabolites, estrone and estriol at the receptor level. ... After menopause, most endogenous estrogen is produced by conversion of androstenedione, secreted by the adrenal cortex, to estrone by peripheral tissues. Thus, estrone and the sulfate conjugated form, estrone sulfate, are the most abundant circulating estrogens in postmenopausal women. Estrogens act through binding to nuclear receptors in estrogen-responsive tissues. To date, two estrogen receptors have been identified. These vary in proportion from tissue to tissue. Circulating estrogens modulate the pituitary secretion of the gonadotropins, luteinizing hormone (LH) and follicle stimulating hormone (FSH), through a negative feedback mechanism. Estrogens act to reduce the elevated levels of these hormones seen in postmenopausal women. Estrogens have an important role in the reproductive, skeletal, cardiovascular, and central nervous systems in women, and act principally by regulating gene expression. Biologic response is initiated when estrogen binds to a ligand-binding domain of the estrogen receptor resulting in a conformational change that leads to gene transcription through specific estrogen response elements (ERE) of target gene promoters; subsequent activation or repression of the target gene is mediated through 2 distinct transactivation domains (ie, AF-1 and AF-2) of the receptor. The estrogen receptor also mediates gene transcription using different response elements (ie, AP-1) and other signal pathways. Recent advances in the molecular pharmacology of estrogen and estrogen receptors have resulted in the development of selective estrogen receptor modulators (eg, clomiphene, raloxifene, tamoxifen, toremifene), agents that bind and activate the estrogen receptor but that exhibit tissue-specific effects distinct from estrogen. Tissue-specific estrogen-agonist or -antagonist activity of these drugs appears to be related to structural differences in their estrogen receptor

Pharmacodynamics

Estradiol acts on the on the estrogen receptors to relieve vasomotor systems (such as hot flashes) and urogenital symptoms (such as vaginal dryness and dyspareunia). Estradiol has also been shown to exert favorable effects on bone density by inhibiting bone resorption. Estrogen appears to inhibit bone resorption and may have beneficial effects on the plasma lipid profile. Estrogens cause an increase in hepatic synthesis of various proteins, which include sex hormone binding globulin (SHBG), and thyroid-binding globulin (TBG). Estrogens are known to suppress the formation of follicle-stimulating hormone (FSH) in the anterior pituitary gland. **A note on hyper-coagulable state, cardiovascular health, and blood pressure** Estradiol may cause an increased risk of cardiovascular disease, DVT, and stroke, and its use should be avoided in patients at high risk of these conditions. Estrogen induces a hyper-coagulable state, which is also associated with both estrogen-containing oral contraceptive (OC) use and pregnancy. Although estrogen causes an increase in levels of plasma renin and angiotensin. Estrogen-induced increases in angiotensin, causing sodium retention, which is likely to be the mechanism causing hypertension after oral contraceptive treatment.

Source: PubChem (NCBI) · pathways from PathBank, Reactome, WikiPathways & PharmGKB.

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The same active ingredient registered across other registries we cover - including different brands.