Inclusion Criteria:
* Women between the ages 21 and 60;
* Pre-menopausal or post-menopausal women may be included;
* May or may not be taking female sex hormones (estrogen with or without progesterone, or their derivatives);
* FSAD, defined as the inability, persistent or recurrent, to obtain or maintain until the conclusion of sexual activity an adequate genital response to sexual arousal (lubrication, warmth and enlargement of the clitoris);
* Women with FSAD who present marked suffering or interpersonal difficulties;
* Stable relationship for more than 6 months, with a sexually active partner;
* Ability to read and understand the Informed Consent Form (ICF) and to answer the questionnaires.
Exclusion Criteria:
* Women who do not agree to use a contraceptive method and who have the capacity to become pregnant during the study;
* Women who do not agree to attempt sexual activity at least twice a week while taking the study medication;
* History of unresolved sexual trauma or abuse;
* Diagnosis of vaginismus, genitopelvic pain/penetration disorder and/or sexual aversion disorder;
* Uncontrolled diabetes at screening visit (HbA1C \> 10%);
* Prior spinal cord injury, with lower limb paralysis;
* History of abdominal or pelvic surgery that may have damaged pelvic nerves, including vulvectomy, colostomy, cytostomy, hysterectomy, or bladder suspension.
* Current testosterone use, or long-term testosterone use (such as chip) within the past 6 months;
* Presence of menstrual irregularity or endocrinopathies that significantly alter the menstrual cycle, preventing Cytocam analyses from taking place at the same time;
* Patients with current depression, characterized by the use or need for use of psychotropic drugs, including bupropion, lithium, or neuroleptics;
* Presence of genital lesions that impair analysis of local adverse effects on the genitalia;
* Presence of diseases that cause excessive vaginal discharge, such as recurrent urinary tract infection, vaginal infection and pelvic inflammatory disease.
* Abnormal Papanicolaou test within the past 3 years;
* History of gynecological cancer (history of uterine dysplasia can be included, provided it has been properly treated for at least 6 months);
* History of pelvic irradiation;
* Use of topical medications in the genital region that may interfere with PSI assessment as well as their absorption or drug interaction, including vaginal estrogens, lubricants, spermicides, creams or gels, vaginal douches;
* History of symptomatic hypotension, or diseases that increase the risk of symptomatic hypotension, such as patient with heart disease (including history of angina and/or heart failure) and nephropathies;
* Current use of nitrates, such as propatylnitrate (Sustrate®), isosorbide (Monocordil®, Cincordil®, Isordil®), nitroglycerin (Nitradisc®, Nitroderm TTS®, Nitronal®, Tridil®) and sosorbitol dinitrate (Isocord®)
* ECG findings that are clinically symptomatic, or that, in the Investigator's judgment, are considered significant and pose a risk to the research volunteer's participation;
* Findings on laboratory tests that, in the Investigator's judgment, are considered significant and offer risk to the research volunteer's participation or may hinder the study analyses;
* TSH outside normal limits for age (participants with hypothyroidism on stable dose of medication, over 3 months, may be included);
* BP outside safe limits: SBP below 90 mmHg or above 170 mmHg; or DBP below 50 mmHg or above 100 mmHg, except for situations such as "white coat" syndrome
* Severe hypertension, considered as use of three or more antihypertensives;
* Diseases that can cause clitoral priapism, such as sickle cell anemia, multiple myeloma or leukemia;
* History of clitoral priapism;
* Current relevant diarrhea, defined as duration over four weeks, association with abdominal pain or malabsorptive syndrome, or presence of mucus, pus, or blood in the stool;
* Pregnant or lactating;
* Current use of nitric oxide donors, guanylate cyclase stimulators (e.g. Riociguat), or 5- phosphodiesterase inhibitors (Sildenafil, Tadalafil, etc.);
* Any disease or condition or physical finding that the Investigator considers significant and that increases the risk of the research participant's participation or may interfere with the results, including serious debilitating diseases, presence of cancer, serious mental illness, persistent abuse of medication.
