Mass Balance Study of [¹⁴C]FXS4640 in Healthy Adult Males

Participants meeting all of the following criteria may be enrolled:

1. Healthy adult Chinese males;
2. Age at the time of signing the informed consent form (ICF): 18-45 years old (inclusive);
3. Body mass index (BMI) range of 19.0-26.0 kg/m² (inclusive), and body weight not less than 50 kg;
4. No plan to father a child or donate sperm within 6 months after the last dose, and voluntarily take strict contraceptive measures (see Appendix 1 for details);
5. Fully understand the purpose, requirements, and risks of this study, and voluntarily sign the ICF;
6. Able to communicate well with the study personnel and to complete the study in accordance with the protocol.

Participants who meet any of the following criteria will not be enrolled:

Auxiliary Examinations:

1. Clinically significant abnormalities found during vital signs, physical examination, chest X-ray (posteroanterior view), ophthalmological examination, digital rectal examination, or abdominal B-ultrasound (liver, gallbladder, pancreas, spleen, kidneys) at screening;
2. Abnormal laboratory tests at screening (hematology, blood chemistry, urinalysis, coagulation function, stool routine and occult blood, thyroid function) that are judged by the investigator to be clinically significant;
3. Abnormal 12-lead ECG findings judged by the investigator to be clinically significant;

4. Clinically significant abnormal results for hepatitis B surface antigen (HBsAg), hepatitis C virus antibody, treponema pallidum antibody, or human immunodeficiency virus antibody as judged by the investigator;

   Medical and Medication History:

5. Use of any prescription drugs, over-the-counter drugs, Chinese herbal medicines, dietary supplements (such as vitamins, calcium supplements), or any drugs that inhibit or induce hepatic drug-metabolizing enzymes within 30 days prior to screening;
6. History of any clinically significant/chronic disease, or any disease or condition that, in the opinion of the investigator, could affect the study results, including but not limited to circulatory, respiratory, endocrine, nervous, digestive, or urinary system, hematological, immunological, psychiatric, and metabolic diseases;
7. History of organic heart disease, cardiac failure, myocardial infarction, angina pectoris, arrhythmia including but not limited to Torsades de Pointes, ventricular tachycardia, atrioventricular block, etc.;
8. History of lactose intolerance (history of diarrhea after drinking milk);
9. History of dysphagia or gastrointestinal diseases that may affect drug absorption, or a history of severe vomiting or diarrhea within 30 days prior to screening;
10. Major surgery within 6 months prior to screening or surgical incision not fully healed; or planning to undergo surgery during the study;
11. History of any known allergy to drugs, food, or environmental factors, especially allergy to components similar to the investigational product, or having an allergic constitution, or history of severe allergic reaction or anaphylactic shock;

12. Symptomatic hemorrhoids or perianal diseases accompanied by regular/active hematochezia, irritable bowel syndrome, or inflammatory bowel disease;

    Lifestyle Habits:

13. Habitual diarrhea or average bowel movement frequency of less than once per day;
14. Alcohol abuse or regular alcohol consumption within 6 months prior to screening, i.e., weekly alcohol consumption exceeding 14 units of alcohol (1 unit = 17.5 mL or 14 g pure alcohol; approximately equivalent to 35 mL of 50° liquor or 350 mL of 5° beer), or an alcohol breath test result > 0 mg/100 mL, or alcohol consumption within 48 hours prior to administration of the investigational product, or inability to abstain from alcohol during the study;
15. Have smoked more than 5 cigarettes per day within 3 months prior to screening, or habitually use nicotine-containing products, or are unable to abstain during the study;
16. History of drug abuse or drug addiction, or a positive urine drug abuse screen;
17. Excessive consumption (more than 8 cups per day, 1 cup = 250 mL) of tea, coffee and/or caffeine-rich beverages, or beverages that affect hepatic drug-metabolizing enzyme activity (such as grapefruit juice) within 3 months prior to screening, or inability to abstain during the study;

18. Have special dietary requirements or are unable to comply with the standardized diet (e.g., intolerance to standard meals); or refusal to abstain from pomelo/grapefruit or their juices, coffee, tea, any caffeine- or xanthine-rich foods (e.g., animal offal, seafood, soy products, etc.) or beverages from 48 hours before dosing until the end of the study;

    Others:

19. Occupation involving long-term exposure to radioactive conditions; or significant radioactive exposure (e.g., ≥2 chest/abdominal CT scans, or ≥3 other types of X-ray examinations) within 1 year prior to screening, or participation in a radiolabeled drug trial within 1 year prior to screening;
20. Have had blood loss or blood donation of ≥400 mL within 3 months prior to screening, or ≥200 mL within 1 month prior to dosing, or have received a transfusion of blood or blood components within 1 month, or plan to donate blood during the investigational product administration period or within 3 months after discontinuation;
21. History of needle phobia or hemophobia, or difficulty with blood collection or inability to tolerate venipuncture blood collection;
22. Have participated in any clinical trial and received an investigational drug, vaccine, or used an investigational device within 3 months prior to screening; or plan to participate in other clinical trials during this study, or not attending the clinical trial in person;
23. Have received any vaccination within 4 weeks prior to screening or plan to receive any vaccination during the study;
24. Have other factors deemed by the investigator to make the participant unsuitable for participation in this study, or participants who withdraw from the study for personal reasons