A Phase 1, 2-part, randomised, double-blind, placebo-controlled, FIH study to determine the safety, tolerability, and PK of single, ascending oral doses (SAD) of BDHK-2009 (Part 1) and multiple oral doses (Part 2) of BDHK-200 in healthy adult participants.

Inclusion Criteria:

- 1. Participants who are able to communicate effectively with the investigator, understand and comply with the trial requirements, voluntarily participate in the trial, and understand and sign the informed consent form.

2. Healthy participants aged 18 to 55 years (inclusive), regardless of gender. 3. Weight ≥ 50 kg (for males) and ≥ 45 kg (for females), with a body mass index (BMI) of 18-26 kg/m².

4. At screening, physical examination, vital signs, 12-lead electrocardiogram (ECG), and laboratory tests (including complete blood count, blood biochemistry, urinalysis, coagulation function, serological virology, thyroid function, etc.) results are either within normal limits or, if abnormal, not clinically significant.

5. Women of childbearing potential (WOCBP) must have negative pregnancy test results at screening and baseline, and must not be pregnant, lactating, or planning pregnancy during the study period. WOCBP must agree to use acceptable contraceptive measures during the treatment period and for at least 90 days after the last dose of the investigational product (whichever is longer).

1. WOCBP is defined as any female who has experienced menarche and has not undergone surgical sterilization (hysterectomy or bilateral oophorectomy) and is not postmenopausal;

2. Non-childbearing potential females are defined as postmenopausal females and premenopausal females who have undergone sterilization surgery. Postmenopausal is defined as the absence of menstruation for ≥ 12 months without alternative medical intervention. Follicle-stimulating hormone (FSH) testing will be performed for subjects with uncertain status, and FSH > 40 mIU/mL can confirm menopause.

   6. Male participants with partners of childbearing potential are eligible for the study only if they agree to use acceptable contraceptive measures during the treatment period and for at least 90 days after the last dose of the investigational product, and agree not to donate sperm during this period. In addition, male participants with partners of childbearing potential must use condoms continuously until at least 90 days after the last dose of the investigational product (whichever is longer).

   Exclusion Criteria:

   • 1. As determined by the investigator, known or persistent psychiatric disorders requiring pharmacological intervention that may interfere with the participant's participation in the study, including but not limited to schizophrenia, bipolar disorder, or major depressive disorder.

     2. Participants with clinically significant abnormalities in any disease or condition, including but not limited to metabolic, hepatic, renal, hematological, pulmonary, cardiovascular, gastrointestinal, urinary, endocrine, neurological, psychiatric, thyroid, or other disorders, as determined by the investigator to be unsuitable for participation in this study.

     3. Presence or suspected presence of active viral, bacterial, fungal, or parasitic infection.

     4. History of recurrent or chronic infections.

     5. Participants with acute illness within 2 weeks prior to screening; participants with clinically significant infections (e.g., upper respiratory tract infection, nasopharyngitis, urinary tract infection, etc.) within 3 months prior to screening; participants with evidence of any infection within 7 days prior to screening; participants with a history of herpes simplex infection or recurrent (>1 episode) herpes zoster or disseminated herpes zoster.

     6. History of epidemic meningococcal infection.

     7. History of splenectomy or functional asplenia.

     8. Participants with positive test results for hepatitis B surface antigen (HBsAg), hepatitis C antibody (anti-HCV), HIV antibody (anti-HIV), or Treponema pallidum antibody.

     9. Participants with a history of active tuberculosis or evidence of active or latent tuberculosis infection at screening.

     10. Participants with a history of allergic tendencies, such as asthma, atopic dermatitis, chronic urticaria, or allergic rhinitis, or with allergies to two or more medications, foods, or pollens; participants with a history of hypersensitivity to the investigational drug or any of its components or to drugs with the same mechanism of action, or with clinically significant allergy history as determined by the investigator to be ineligible for enrollment.

     11. Participants who have participated in another interventional clinical study and received an interventional treatment (including investigational drugs and investigational medical devices) within 30 days prior to the first dose of the study drug, or within 5 half-lives of the study drug (whichever is longer).

     12. Participants with a history of drug abuse within 12 months prior to screening, or participants with positive urine drug screening results.

     13. Participants who have used any strong inducers or strong inhibitors of the hepatic metabolic enzyme CYP3A within 14 days or 5 half-lives prior to administration of the investigational drug (whichever is longer).

     14. Participants who have used any prescription medications within 14 days prior to administration of the investigational drug, or any over-the-counter medications, herbal medicines, or dietary supplements within 7 days prior to administration of the investigational drug, unless the investigator determines that the medication is not clinically significant.

     15. Participants who have consumed any foods or beverages containing substances that may induce or inhibit hepatic metabolic enzymes (such as grapefruit, Seville orange, or star fruit, etc.) within 7 days prior to administration of the investigational drug, or who are unable to avoid consumption of foods or beverages containing caffeine within 48 hours prior to administration of the investigational drug and throughout the inpatient study period.

     16. Participants who consumed more than 14 units of alcohol per week within 1 month prior to screening (1 unit of alcohol is approximately equivalent to 360 mL of beer, or 45 mL of spirits with 40% alcohol content, or 150 mL of wine), or who consumed any alcohol products within 24 hours prior to dosing, or who have positive alcohol screening test results.

     17. Heavy smokers or participants who smoked more than 5 cigarettes per day within 3 months prior to dosing, and who are unable to abstain from using more than 5 tobacco or nicotine-containing products (including nicotine patches) per week from screening through the end of the study.

     18. Participants who donated blood or experienced blood loss ≥ 200 mL within 1 month prior to screening or dosing, or who donated blood or experienced blood loss ≥ 400 mL within 3 months prior to dosing, or who have difficult venous access or are unable to tolerate blood sampling.

     19. At screening or baseline, 12-lead electrocardiogram (ECG) findings showing clinically significant abnormalities, including but not limited to: QTcF > 450 ms, or other arrhythmias or morphological abnormalities as determined by the investigator that may increase participant risk or interfere with data interpretation.

     20. Participants with dysphagia or special dietary requirements who are unable to accept a standardized diet (e.g., severe food allergies).

     21. Participants who have undergone major surgical procedures within 3 months prior to screening or who are planning to undergo surgery during the trial period.

     22. Participants who have received vaccination within 8 weeks prior to screening, or who plan to receive vaccination during the study or within 8 weeks after administration of the study drug.

     23. Any other condition that, in the opinion of the investigator, makes the participant unsuitable for participation in the study.