Inclusion Criteria:
* Healthy male and female participants aged 18 to 45 years, inclusive, at screening.
* Body mass index (BMI) of 19 to 26 kg/m², inclusive, and body weight ≥45 kg.
* Participant fully understands the purpose, content, procedures, and potential risks of the study, voluntarily agrees to participate, and signs the informed consent form.
* Able to communicate well with the investigator and willing and able to comply with the lifestyle restrictions and study procedures specified in the protocol.
Exclusion Criteria:
* History or presence of any disease or dysfunction that, in the investigator's judgment, may affect the clinical trial, including but not limited to chronic or severe diseases of the central nervous system, cardiovascular system, respiratory system, digestive system, urinary system, endocrine system, blood and lymphatic system, or psychiatric disorders.
* Abnormal QT/QTc at baseline, including QTcF ≥450 ms; other risk factors for torsades de pointes (e.g., heart failure, hypokalemia, hypomagnesemia, family history of long QT syndrome); or potential bundle branch block.
* Clinically significant abnormalities on physical examination, vital signs, hematology, blood chemistry, urinalysis, coagulation, thyroid function tests, chest X-ray, abdominal ultrasound, or 12-lead ECG.
* History of severe drug allergy (known or suspected allergy to NH302 injection or its excipients), severe specific allergic disease/history (e.g., asthma, urticaria, eczematous dermatitis), or severe allergic constitution (two or more food or drug allergies).
* Medical conditions that may induce or worsen somnolence or dizziness, including active dizziness, motion sickness, history of orthostatic hypotension, history of syncope, history of vertigo (including Meniere's disease), moderate-to-severe sleep apnea syndrome, narcolepsy, or other conditions manifested by somnolence or dizziness.
* Need to drive, work at heights, operate precision machinery, or perform other activities requiring high alertness within 24 hours after discharge from the study and unable to suspend these activities.
* History of drug abuse, drug dependence, or substance abuse within 1 year before screening, or positive urine drug screen.
* Use of any hepatic enzyme inhibitor or inducer within 1 month before screening (e.g., inducers: phenobarbital, rifampicin, carbamazepine, phenytoin, dexamethasone; inhibitors: fluvoxamine, S-mephenytoin, propofol, isoniazid, phenothiazines).
* Received an inactivated vaccine within 1 month before screening; received an inactivated or live attenuated vaccine within 3 months before screening; or plans to receive an inactivated or live attenuated vaccine during the study.
* Blood loss or donation of more than 400 mL within 3 months before screening (excluding menstrual bleeding in women); transfusion or receipt of blood products exceeding 400 mL within 3 months before the trial; or plans to donate blood during the study or within 1 month after study completion.
* History of surgery within 3 months before screening, incomplete recovery from surgery, or planned surgery during the study.
* Use of any prescription drug, over-the-counter drug, herbal medicine, or dietary supplement (including vitamins and health products) within 2 weeks before dosing or within 5 half-lives of the drug, whichever is longer.
* History of alcohol abuse within 6 months before screening (i.e., more than 14 standard units per week; 1 unit = 360 mL beer, 45 mL of 40% spirits, or 150 mL wine), positive alcohol breath test (result \>0), or inability to abstain from alcohol during the study.
* Positive smoking test; smoking ≥5 cigarettes per day within 6 months before screening; or inability to stop using any tobacco product (including nicotine gum or transdermal nicotine patches) during the study.
* Intake of caffeine-containing food or beverages (e.g., coffee, strong tea, chocolate, caffeine-containing carbonated drinks, cola) within 48 hours before screening.
* Intake of any glucose-rich beverage or food within 48 hours before screening.
* Special dietary requirements, inability to comply with a standardized diet, or dysphagia; or anorexia, dieting, or significant abnormal diet (e.g., dieting, low sodium) started within 4 weeks before screening.
* Positive or non-negative results for hepatitis B surface antigen (HBsAg), hepatitis C antibody (HCV-Ab), HIV antibody (HIV-Ab), or Treponema pallidum (TP) antibody.
* Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) \>1.5 × upper limit of normal (ULN); or creatinine (Cr), blood urea nitrogen (BUN), or urea \>ULN.
* Difficulty with blood sampling, intolerance to venipuncture, or history of hemophobia or needle phobia.
* Pregnant or breastfeeding women at screening; or participants who refuse to use effective contraception (e.g., abstinence, intrauterine device) during the study and within 3 months after study completion, or who plan to donate sperm or oocytes.
* Participation in any clinical trial within 3 months before dosing or still in the follow-up period of another trial.
* Poor expected compliance or any other condition that, in the investigator's judgment, makes the participant unsuitable for the study.
