Inclusion Criteria:

• 1. Overall good general health.
• 2. Age 18-35 years at time of enrollment.
• 3. BMI
• 1. Initial dose-finding cohort: BMI \< 30 kg/m2; thereafter no BMI limit
• 4. Intact uterus with at least 1 ovary.
• 5. Regular menstrual cycles that occur every 21-35 days:
• 1. If patient is postpartum or post-second trimester abortion, she must have 3 menses (2 cycles) prior to enrollment.
• 2. If patient had a first trimester abortion or pregnancy loss, she must have one spontaneous menses prior to enrollment.
• 6. Negative urine pregnancy test at screening visit and at time of drospirenone administration.
• 7. Consistent use of a barrier method or other non-hormonal birth control method throughout the study, or otherwise not at risk for pregnancy.
• 8. Ovulatory as confirmed by a documented screening progesterone (P4) level ≥3ng/ml at screening visit.
• 9. Willingness and ability to abstain from medications and supplements known to induce/inhibit CYP3A4 during the study period
• 10. Willingness and ability to comply with the protocol requirements.
• 11. Lives within the study site catchment area or within a reasonable distance from the site.

Exclusion Criteria:

• 1. Have a known hypersensitivity or contraindications to drospirenone.
• 2. Currently taking any known CYP3A4 inducers/inhibitors.
• 3. Medical conditions that affect liver function (e.g., hepatitis, cirrhosis; assessed via participant self-report).
• 4. Medical conditions that affect kidney function (e.g., chronic kidney disease, primary renal disease; assessed via participant self-report) or use of medications that can affect kidney function and/or electrolyte balance (e.g., ACE inhibitors, diuretic medications; assessed via participant self-report).
• 5. A known history of or presence of hyperkalemia (potassium ≥4.5mEq/L) or renal impairment (creatinine of ≥1.1mg/dL) at screening visit.
• 6. Known or suspected current alcohol dependence syndrome or any illicit drug use that may affect the metabolism of the drospirenone.
• 7. Undiagnosed abnormal uterine/genital bleeding.
• 8. Uncontrolled thyroid disorder.
• 9. Use of long-acting injectable hormonal contraceptive within the past 6 months prior to enrollment unless the patient has had at least one spontaneous menstrual cycle since the last injection.
• 10. Recent use of hormonal oral, patch, intravaginal, or intrauterine contraception unless that patient has had at least one spontaneous menstrual cycle since discontinuation.
• 11. Currently breastfeeding or are within 30 days of discontinuing breastfeeding unless the patient has already had a menses following discontinuation.
• 12. Planning on undergoing major surgery during study participation.
• 13. Planning significant weight loss during the study related to bariatric surgery, dieting, or other causes.
• 14. Planning pregnancy during their anticipated months of study participation