Inclusion Criteria:

• Postmenopausal women not older than 70 years of age at the time of screening (menopause defined as ≥ 6 months amenorrhea with serum follicle-stimulating hormone [FSH] levels ≥ 40 IU/L and serum E2 < 73 pmol/L).
• Body mass index 18-30 kg/m2 inclusive.
• Good physical and mental health, as judged by the Investigator, determined by medical history, physical examination, clinical laboratory values, vital signs, and electrocardiogram (ECG) recording.
• Willing to give written informed consent.
• Either > 50 hot flushes per week or < 10 hot flushes per week

Exclusion Criteria:

• Clinically significant abnormal results of routine hematology, serum biochemistry, urinalysis, and/or ECG in the opinion of the Investigator at screening.
• Clinically significant abnormal mammogram (presence of any non-cystic mass) within one year before study start.
• Clinically significant abnormalities of the uterus and/or ovaries detected by examination and/or ultrasound (non-physiological ovarian mass or significant uterine pathology or an endometrium greater than 6 mm).
• A cervical smear with clinically relevant abnormal cytology within one year before study start.

• Previous use of estrogen/progestogen within:

  • 6 months for depot preparations.
  • 8 weeks for oral preparations or progestogen containing intrauterine device (IUD).
  • 4 weeks for transdermal preparations.
• Use of hormone containing implant at any time.

• Contraindications for using steroids:

  • A history of, or existing thromboembolic, cardiovascular, or cerebrovascular disorder.
  • A history of, or existing conditions predisposing to, or being prodrome of, a thrombosis.
  • A known defect in the blood coagulation system (e.g. deficiencies in antithrombin-III [AT-III], protein C, S, and activated protein C [APC] resistance).
  • A medical history positive for the presence of more than one risk factor for vascular disease (e.g.

dyslipoproteinemia; diabetes mellitus; hyperhomocysteinemia; systemic lupus erythematosus; chronic inflammatory bowel disease; smoking; venous thromboembolism in sibling or parent below the age of 50, or arterial disease in sibling or parent below the age of 30-35).

• Hypertension, i.e. systolic blood pressure >160 mm Hg and/or diastolic blood pressure >100 mm Hg.
• Disturbance of liver function: cholestatic jaundice, a history of jaundice in pregnancy or jaundice due to previous estrogen use, Rotor syndrome and Dubin-Johnson syndrome.
• Known or suspected estrogen-dependent tumors or endometrial hyperplasia
• Undiagnosed vaginal bleeding.
• Porphyria.

• A history during pregnancy or previous estrogen use of severe pruritus, herpes gestationis, or deterioration of otosclerosis.

  • Any medication (including over-the-counter [OTC] products) from 14 days prior to the day of dosing except for occasional non-steroidal anti-inflammatory drugs (NSAID; e.g. ibuprofen); paracetamol is not permitted.
  • Any enzyme affecting drugs from 30 days prior to Day 1 and the use of griseofulvin, primidone, oxcarbazepine, topiramate, felbamate, or herbal remedies containing hypericum perforatum (St. John’s wort).
  • Presence of significant allergies or other serious diseases.
  • Smoking more than 10 cigarettes or equivalent per day.
  • Administration of investigational drugs within 3 months before start of study medication.
  • A history of (within 12 months) alcohol or drug abuse.