Dydrogesterone is a retroprogesterone, a unique class of progestogens with a modified molecular structure that enhances its stability and selectivity. Its mechanism includes:

1. Progesterone Receptor Agonism: Binds to progesterone receptors in the endometrium, promoting secretory changes necessary for implantation and pregnancy maintenance (Lippincott).
2. Endometrial Support: Prevents estrogen-induced endometrial hyperplasia by balancing estrogen’s proliferative effects (Lange).
3. Pregnancy Maintenance: Supports the luteal phase in assisted reproductive technology (ART) and prevents miscarriage in progesterone-deficient women (BNF).

Dydrogesterone does not suppress ovulation, making it suitable for fertility treatments.

1. Luteal Phase Support: Used in ART and infertility treatments to prepare the endometrium for implantation.
2. Endometriosis: Reduces pain and inflammation by opposing estrogen’s effects on endometrial tissue (Lippincott).
3. Dysmenorrhea: Alleviates painful menstruation by stabilizing the endometrium.
4. Irregular Menstruation: Regulates cycles in women with progesterone deficiency.
5. Threatened or Recurrent Miscarriage: Prescribed to maintain pregnancy in progesterone-deficient women (BNF).
6. Hormone Replacement Therapy (HRT): Combined with estrogen to prevent endometrial hyperplasia in postmenopausal women (Lange).

• Endometriosis: 10 mg 2–3 times daily from day 5 to 25 of the menstrual cycle (BNF).
• Dysmenorrhea: 10 mg twice daily from day 5 to 25 of the cycle.
• Irregular Menstruation: 10 mg twice daily from day 11 to 25 of the cycle.
• Threatened Miscarriage: 40 mg once, followed by 10 mg every 8 hours until symptoms resolve.
• Recurrent Miscarriage: 10 mg twice daily until week 20 of pregnancy.

HRT: 10 mg daily for 14 days per 28-day cycle, combined with estrogen

• Common: Nausea, headache, breast tenderness, bloating, and mild gastrointestinal disturbances.
• Rare: Breakthrough bleeding, weight changes, and mood swings.
• Serious: Allergic reactions (e.g., rash, itching) and hepatic dysfunction (very rare) (Lippincott).

• Absolute Contraindications: Known hypersensitivity to dydrogesterone, undiagnosed vaginal bleeding, or history of progesterone-dependent tumors (BNF).
• Relative Precautions: Liver dysfunction, history of depression, or thromboembolic disorders (though dydrogesterone has minimal thrombogenic risk compared to other progestins) (Lange).
• Monitoring: Regular liver function tests in long-term users and monitoring for signs of thromboembolism in high-risk patients.

• nzyme Inducers: Drugs like rifampicin, phenytoin, and carbamazepine may reduce dydrogesterone levels by increasing hepatic metabolism (BNF).
• Anticoagulants: Potential interaction with warfarin; monitor INR closely.
• Other Hormonal Therapies: Avoid concurrent use with other progestins or estrogens unless prescribed as part of HRT (Lippincott).

Generic Names in Pharmacy

• Active Ingredient: Dydrogesterone.

Brands: Marketed as Duphaston; generics may be labeled as dydrogesterone