To evaluate the safety and tolerability of HL-300 ointment following single and multiple topical administrations in healthy Chinese adult volunteers.

This study is a single-center, randomized, double-blind, placebo-controlled, single and multiple ascending dose Phase I clinical study in healthy volunteers. A total of 36 volunteers are planned to be enrolled, with 4 in Cohort 1, 8 in Cohort 2, and 12 in each of Cohort 3 and Cohort 4.

In the single ascending dose (SAD) part (Cohorts 1-3), volunteers in each cohort will receive a single dose on Day 1 (D1). Blood samples will be collected from the volunteers at the time points specified in the protocol, and volunteers will be discharged after completing the final blood collection on D8. The blood sampling timepoints for subsequent dose cohorts may be adjusted based on the results of the preceding cohorts.

In the multiple ascending dose (MAD) part (Cohort 4), volunteers will apply the study drug twice daily from D1 to D7 (the dosing frequency during the MAD period may be appropriately adjusted based on the PK characteristics of the single dose). Blood sampling timepoints will be adjusted based on the dosing results, and volunteers will be discharged to enter the safety follow-up period after completing the final blood collection.

Volunteers in different dose cohorts will be enrolled sequentially, and the next cohort will only proceed provided that the 7-day tolerability evaluation of the preceding cohort indicates safety and tolerability. Whether to add subsequent dose cohorts will be determined based on the results obtained from the completed dose cohorts.

Inclusion Criteria:

1. Male or female volunteers aged ≥ 18 and ≤ 45 years
2. Males weighing ≥ 50 kg and females weighing ≥ 45 kg, with a body mass index (BMI) within the range of 19.0 to 26.0 kg/m² (inclusive), where BMI = weight (kg) / height² (m²);
3. Women of childbearing potential (WOCBP) must confirm that they are not pregnant or lactating, and may only enter the study after a pregnancy test (e.g., based on HCG beta-subunit testing) is performed (the date of the last menstrual period must be recorded);
4. Volunteers and their partners must voluntarily adopt effective contraceptive measures for at least 6 months after the administration of the investigational product; volunteers must have no plans to donate sperm or eggs for at least 6 months from the screening period to after administration;
5. Volunteers must understand the informed consent form, voluntarily participate in the study, and sign the informed consent form; the informed consent form must be signed prior to the initiation of any study procedures.

Exclusion Criteria:

1. Individuals with a history of malignant tumors, or any clinically severe disease (past or present) involving the circulatory, endocrine, nervous, digestive, respiratory, genitourinary, hematological, immunological, psychiatric systems, or metabolic disorders, or any other disease that may interfere with the study results;
2. Volunteers who, in the opinion of the investigator, have clinically relevant skin diseases that are contraindicated for the study or may interfere with the assessment of the administration site, including psoriasis, eczema, acne, atopic dermatitis, dysplastic nevi, other skin lesions, or a history of skin cancer;
3. Individuals with a history of active tuberculosis, a history of frequent infections within 1 year prior to screening, or a history of recurrent viral infections (such as recurrent oral herpes, genital herpes, or herpes zoster) within 3 months prior to administration; those who have experienced an infection deemed clinically significant by the investigator within 1 month prior to screening, including acute or chronic infections such as local infections (abscesses, furuncles, carbuncles, etc.), respiratory tract infections, genitourinary tract infections, or systemic infections;
4. Individuals suspected of being allergic to the investigational drug or any of its components, or with a history of allergic diseases (e.g., allergic rhinitis, allergic asthma, etc.), drug allergy history, skin allergy history (including but not limited to allergies to adhesive patches, or contact dermatitis to metals, cosmetics, or household products), or those known to have an atopic constitution, such as a history of allergy to two or more drugs and foods.
5. Those with vital signs (systolic blood pressure <90 mmHg or >140 mmHg, diastolic blood pressure <50 mmHg or >90 mmHg; heart rate <50 bpm or >100 bpm) or abnormalities in physical examination, electrocardiogram (ECG), chest X-ray, or laboratory tests that are clinically significant (as determined by the clinical research physician);
6. Those whose white blood cell count, neutrophil count, lymphocyte count, or hemoglobin in the routine blood test are outside the normal reference range and are deemed clinically significant by the investigator;
7. ALT > 1.5 times the upper limit of normal (ULN), or AST > 1.5 times ULN, or total bilirubin > 1.5 times ULN;
8. Those with positive test results for hepatitis B surface antigen (HBsAg), hepatitis C virus antibody (HCV-Ab), human immunodeficiency virus (HIV) antibody, or Treponema pallidum antibody (TP-Ab);
9. Those with a positive dermatographia (skin scratch) test;