Subdermal Implant-bioabsorbable Gestrinone Pellet for Endometriosis Pelvic Pain Treatment

Inclusion Criteria 1. Willingness to provide informed consent 2. Woman aged between 18 and 50 years 3. Body weight between 50 ± 5 kg and 90 ± 5 kg 4. Pelvic pain secondary to endometriosis surgically treated with refractory symptoms, independent of pain intensity 5. Endometriosis documented by biopsies (histopathological examination) 6. Last endometriosis surgery at least 3 months before randomization 7. Not planning to become pregnant within 12 months after the screening visit or be surgically sterilized 8. Absence of changes in the breast (BI-RADS1 and BIRADS-2 classification) documented by an imaging report (mammogram for women aged \> 40 years or bilateral breast ultrasound for women aged \< 40 years) performed less than 12 months before randomization 9. Agreement not to use other hormones (estrogens, androgens and progestins) in any pharmaceutical form during the study Exclusion Criteria 1. Chronic severe disorders, including metastatic malignancies, end-stage renal disease with or without dialysis, clinically unstable heart disease, or any other disorder that, in the opinion of the investigator, excludes the participant from the study 2. Suspected or confirmed diagnosis of immunodeficiency based on medical history and/or physical or laboratory examination 3. Other medical or psychiatric conditions, including recent laboratory abnormalities (within the last 12 months) that may increase risks to the study participant or, at the discretion of the investigator, make the participant inappropriate for the study 4. Personal history of thromboembolic events 5. Use anticoagulant medication 6. Contraindication to the use of hormonal contraceptives 7. Suspected or confirmed pregnancy 8. Breastfeeding 9. Current or recurrent pelvic inflammatory disease or other conditions that increase the risk of pelvic infections 10. Postpartum endometritis or septic miscarriage in the last 3 months 11. Abnormal uterine bleeding of unknown etiology 12. Congenital or acquired uterine anomalies, including fibroids (leiomyomas or fibromas) that cause distortion of the uterine cavity 13. Uterine or cervical malignancy 14. Suspected or confirmed diagnosis of estrogen-dependent neoplasm, including breast cancer 15. Cervicitis or vaginitis, including bacterial vaginosis or another uncontrolled lower urinary tract infection 16. Cervical dysplasia 17. Active liver disease or dysfunction 18. Benign or malignant liver tumors 19. Allergy or intolerance to levonorgestrel, gestrinone or any other ingredient or component of the Kyleena® formulation or hormonal pellets 20. Previously inserted intrauterine device or levonorgestrel-releasing intrauterine system that has not been removed 21. History of recent trophoblastic disease and continued high HCG levels 22. Bacterial endocarditis 23. Hyperandrogenism at the time of randomization, defined by: hirsutism: Ferriman-Gallwey score ≥ 8; clitoromegaly: defined by the Clitoral index ≥ 35 mm2, acne: defined by the IGA scale (Investigator's global assessment) grade 5 - severe inflammatory acne dominates the area and there is a large number of comedones, pustules, papules and cystic acne; alopecia with sequelae of scalp thinning 24. Diagnosis of polycystic ovary syndrome 25. Participation in another pharmacotherapeutic or investigational medical device study within 30 days prior to the start of study treatment 26. Tobacco Use 27. Use of testosterone-derived hormones and analogues in the last month