This is a Phase 1, randomized study to evaluate the rate of nausea in healthy premenopausal study participants following a single dose of BMT with or without a single 8 mg po dose of Zofran given 30 minutes before BMT dosing.

This is a Phase 1, randomized study to evaluate the rate of nausea in healthy premenopausal study participants following a single dose of BMT with or without a single 8 mg po dose of Zofran given 30 minutes before BMT dosing. The study consists of a 21-day screening period for subject eligibility followed by a 1-day double-blind period in which all subjects receive a single open-label dose of 1.75 mg SC BMT after receiving a single blinded dose of Zofran (ondansetron) 8 mg or placebo. Approximately 228 subjects will be enrolled at up to two study sites in the United States. Safety and tolerability of BMT administration will be summarized and assessed.

Key Inclusion Criteria:

1. Willing and able to provide written informed consent prior to participating in the study.
2. Female subjects ≥18 to 55 years of age (inclusive) and premenopausal as defined by the modified STRAW criteria (specifically, Stage -5 [menses variable to regular] through Stage 1 [≥2 skipped cycles and an interval of amenorrhea ≥60 days]).
3. Able to communicate clearly with the Principle Investigator (PI) and staff; able to read English, complete questionnaires, and understand study procedures.
4. Able to complete all screening period evaluations, stay in the clinic testing facility for minimum of 4 hours following dose of BMT.
5. In good general health, free from clinically significant medical or psychiatric illness or disease (as determined by medical/surgical history, physical examination, weight, 12-lead ECG, and clinical laboratory tests).

Key Exclusion Criteria:

1. Postmenopausal female, designated by having amenorrhea for ≥12 months.

2. Has current or recent (within 6 months) history of gastrointestinal disease, or any surgical or medical condition such as Crohn's disease or liver disease, that could potentially alter the absorption, metabolism, or excretion of the study drug.

3. Has any clinically significant medical condition, physical exam finding, or ECG abnormality, or clinically significant abnormal value for hematology, serology, clinical chemistry, or urinalysis at Screening, or at admission to the study center, as assessed by the PI.

4. Has any of the following:

   - History or current diagnosis of uncontrolled hypertension defined as: Two (2) sequential assessments (at least 5 minutes apart and no more than 15 minutes apart) at levels >140 mmHg SBP or 90 mmHg DBP and/or treatment for hypertension that has been changed at least once in the 4 weeks before Screening.

   - Renal dysfunction (creatinine clearance < 80 mL/min using Cockcroft Gault calculation).

5. History or presence of malignancy within the past 5 years, with the exception of adequately treated localized skin cancer (basal cell or squamous cell carcinoma), which is allowed.

BMT will be administered in an open-label manner. Administration of Zofran or placebo will be double-blinded using an over-encapsulation (OE) technique . The randomization assignments and code will not be provided to the Sponsor, sites, or subjects until the study database has been locked, except as unblinding is required for non-study personnel in the regulatory reporting of serious adverse events (SAEs) or for other safety-related reasons.