Effects of Simvastatin on Uterine Leiomyoma Size

Inclusion Criteria: * Signed informed written consent. * Gender: female. * Age: 18-55 years at time of signing consent. * BMI of subjects: \< 45 kg/m2. * Uterine fibroids: * Diagnosed by ultrasound (MRI will be used only if ultrasound is inconclusive). * Number: any number of fibroids. * Location: submucosal or intramural. * At least one fibroid of diameter \> 3cm. * Symptoms: one or more of the following symptoms of heavy menstrual bleeding (HMB), defined as: Experienced cyclic (22 to 35 days) abnormal uterine bleeding (heavy or prolonged) in at least 3 of the last 6 menstrual periods, including menstrual bleeding lasting 5 or more days or heavy bleeding per participant recall. Examples of heavy bleeding may include, but are not limited to the following: * Requires the use of double protection to manage menstrual bleeding. * Menstrual bleeding accompanied by the sensation of "gushing" or "flooding". * Saturates more than 1 tampon or sanitary pad per hour for 3 or more consecutive hours. * Regularly needs to change the tampon or sanitary pad at night or regularly soils bedclothes. * Heavy bleeding that affects work, school, or social activities. * Pelvic pain/ pressure likely caused by fibroids. * Plan for surgery (hysterectomy or myomectomy). * Normal Pap smear within the last year. * Use of contraception during study such as non-hormonal oral contraceptives, intrauterine devices (IUD)/ intrauterine systems (IUS), barrier contraceptives, abstinence or sterilization. Exclusion Criteria: * Pregnancy or lactation. * Previous or current uterine, cervical or ovarian cancer. * Current endometrial hyperplasia or history of atypical endometrial hyperplasia. Endometrial biopsy will be done during screening (if not done within last 12 months). * Suspicion of leiomyosarcoma. * Recent rapid growth of fibroids (i.e. doubling in size within 1-6 months period). * Unevaluated gynecologic abnormalities (unexplained vaginal bleeding, cervical dysplasia, or abnormal adnexal/ovarian mass). * Menopausal status. * Surgery is urgently indicated (\< 3 months) for medical or social reasons. * Hemoglobin ≤ 6 g/dL. * Currently enrolled in another investigational study. * Mental condition or other barrier preventing informed written consent. * Allergy or hypersensitivity to simvastatin. * Current use of simvastatin or other drugs of the same class. * Concomitant administration of strong CYP3A4 inhibitors including itraconazole, ketoconazole, posaconazole, voriconazole, erythromycin, clarithromycin, telithromycin, HIV protease inhibitors, boceprevir, telaprevir, nefazodone, and cobicistat-containing products. * Concomitant administration of gemfibrozil, cyclosporine, or danazol, verapamil, diltiazem, amiodarone, diltiazem, dronedarone, amlodipine, ranolazine, lomitapide, and grapefruit juice. * Active liver disease, which may include unexplained persistent elevations in hepatic transaminase levels.( elevation of aspartate transaminase and/or alanine transaminase \> 2 s.d. above the normal range at screening visit) * Known increased risk or diagnosis of a myopathy.