Evaluation of the Pharmacokinetics, Safety, and Tolerability of IM Letrozole LEBE in Healthy Post-menopausal Women

The study consists of 1 Screening Period and 2 treatment periods. Evaluation of eligibility and allocation of subject number to the volunteers will be performed after Screening. It is planned that subjects will be enrolled in three groups of approximately 30 subjects in each group (Groups 1 to 3), in order to ensure 15 completed subjects per group in Treatment Period 1 and Treatment Period 2. In Treatment Period 1, each subject will sequentially receive 1 dose daily of oral Femara (2.5 mg) over a period of 14 days followed by a single intramuscular (IM) dose of Letrozole LEBE (after a washout period) in Treatment Period 2. Ascending doses of Letrozole LEBE will be given to Groups 1, 2 and 3. Safety and tolerability will be assessed in all groups by the incidence and severity of Adverse Events (AEs) and Serious AEs (SAEs), concomitant medication use, vital sign assessments, clinical laboratory evaluations, 12 lead ECGs, physical examination, and body weight/BMI. The end of the clinical trial will be the last visit of the last subject at Day 197 of Treatment Period 2 or any additionally required 4-weeks safety follow up visits, when plasma levels of letrozole are detectable, whichever occurs later. Those remaining subjects with detectable plasma levels of letrozole could be followed every 4 weeks. The sample size was estimated based on a minimum number necessary to obtain a preliminary assessment regarding the drug's PK and safety profile over the planned dose range. No formal sample size calculation was made for this study.