Inclusion Criteria:  Postmenopausal, defined as:  at least 12 months of spontaneous amenorrhea prior to signing of informed consent, or at least 6 months of spontaneous amenorrhea prior to signing of informed consent with serum follicle-stimulating hormone (FSH) levels > 40 mIU/mL and a serum estradiol concentration of < 30 pg/mL, or at least 6 months after hysterectomy at signing of informed consent with serum FSH levels > 40 mIU/mL and a serum estradiol concentration of < 30 pg/mL, or surgical bilateral oophorectomy with or without hysterectomy at least 6 weeks prior to signing of informed consent. Moderate to severe hot flash (HF) associated with the menopause and seeking treatment for this condition. Participant has completed Hot Flash Daily Diary (HFDD) for at least 11 days during the two weeks preceding baseline visit, and participant has recorded at least 50 moderate or severe HF (including night-time HF) over the last 7 days that the HFDD was completed (assessed at the Baseline Visit).  Exclusion Criteria:  Any clinically significant prior or ongoing history of arrhythmias, heart block and QT prolongation either determined through clinical history or on ECG evaluation. Any active ongoing condition that could cause difficulty in interpreting vasomotor symptoms (VMS) such as: infection that could cause pyrexia, pheochromocytoma, carcinoid syndrome. Current or previous history of any malignancy (except basal and squamous cell skin tumors). Uncontrolled or treatment-resistant hypertension. Women with mild hypertension can be included in the study if they are medically cleared prior to study participation. A history of untreated hyperthyroidism or hypothyroidism. Treated hypothyroidism with normal thyroid function test results during screening and a stable (for >= 3 months before signing of informed consent) dose of replacement therapy is acceptable. Any unexplained post-menopausal bleeding. Clinically relevant abnormal findings on mammogram. Abnormal liver parameters. Disordered proliferative endometrium, endometrial hyperplasia, polyp, or endometrial cancer diagnosed based on endometrial biopsy during screening.