This is a three-part Phase Ia study to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of single ascending doses of SYHA1805.

This trial is divided into three parts: 1) The first part: Four Chinese healthy subjects will be included in the pre-test group to evaluate the safety, tolerability and pharmacokinetics after taking SYHA1805 tablets; 2) The second part: To evaluate the safety, tolerability, pharmacokinetics and pharmacodynamic characteristics, several single ascending doses of SYHA1805 tablets or matching placebo tablets will be randomly administered to 24 Chinese healthy subjects under fasting condition; 3) The third part :To evaluate the food effect on the pharmacokinetic characteristics, a single dose SYHA1805 tablets will be administered to 12 Chinese healthy subjects under fed or fasted condition.

Inclusion Criteria:

• Age: 18 to 45 years of age inclusive;
• Weight: Body weight ≥50 kg, body mass index (BMI) within the range of 19-28 kg/m2 (inclusive);
• Overtly healthy as determined by medical evaluation including comprehensive physical examinations, vital signs, laboratory examinations, ECG examination, color Doppler ultrasound (abdominal color Doppler ultrasound, heart color Doppler ultrasound), chest X-ray, etc.;
• Agree to use highly effective contraceptive methods (such as condoms or intrauterine devices, contraceptive drugs) during the clinical trial period (screening period to 30 days after the last dose). Male subject refrains from sperm donation;
• Fully understand the content and possible adverse reactions of the test drug, have the ability to communicate with investigators normally, and able to comply with the research requirements(such as: visit on time, and follow the procedures, restrictions and requirements of the protocol);
• Volunteer to participate in the study and sign the informed consent form.

Exclusion Criteria:

• Have history or other underlying risk factors of torsade de pointes ventricular tachycardia, short QT syndrome, long QT syndrome. Have first-degree relatives (biological parents, siblings or children) who suffered from sudden death in young age (less than/equal to 40 years old), drowning or sudden infant death syndrome of unknown cause ;

• Have history of malignant tumors, mental illness, depression, anxiety, and epilepsy;

• Have history of drugs abuse in the past 3 years. or positive drug test at screening;

• Have history of clinically significant drug allergies, or a history of atopic allergic diseases (asthma, urticaria, eczema dermatitis), or those who are known to be allergic to experimental drug excipients or the same type of drugs;

• The investigator determines that the subjects have disease that affect drug absorption, distribution, metabolism, or excretion, such as:

  • History of inflammatory bowel disease, gastritis, ulcers, bile duct stones, gastrointestinal or or rectal bleeding;
  • History of major gastrointestinal surgery (gastrectomy, gastrointestinal anastomosis, or bowel resection);
  • History or clinical evidence of pancreatic injury or pancreatitis;
  • ALT, AST, and total serum bilirubin are greater than 2 times the upper limits of normal (ULN) or other liver function test abnormalities, and the abnormalities are determined by the investigator to have clinical significance, suggesting liver disease or liver damage;
  • Renal function suggests that the creatinine clearance rate is less than 90 mL/min, or has urinary tract obstruction or difficulty in emptying urine;

• HBsAg positive, HCV-Ab positive, HIV-Ab positive or syphilis antibody positive during the screening period;

• Have history of alcohol abuse within 6 months before screening, have a positive alcohol breath test during the screening period and the baseline period, or cannot stop drinking during the entire study period; Subjects smoke more than 5 cigarettes per day within the 3 months prior to screening, have a positive nicotine test at screening, or cannot give up smoking during the entire study period;

• Have participated in clinical trials of any drug or medical device within 3 months before screening；

• Have undergone major surgery within 3 months before screening, or have had severe infections within 4 weeks before screening;

• Have had significant change in diet or exercise habits within 3 months before screening, such as weight loss, diet, exercise, etc.;

• Donated blood ≥500 mL within 4 weeks before screening, or had severe blood loss in excess of 500 mL, or received blood transfusion within 8 weeks prior to screening;

• Have used any prescription drugs within the 4 weeks before screening, including antibiotics or Chinese herbal medicines; have used any Over-the-Counter (OTC) medications or food supplements (such as vitamins and calcium) within the 2 weeks before screening except for paracetamol (maximum 1000 mg per day), ibuprofen (maximum 2400 mg per day) and topical OTC drugs; have taken a drug within its 5 half-lives prior to the first dose of the study drug;

• Smoking, consumption of alcohol or food/beverages containing xanthine or caffeine, strenuous exercise, or taking foods that affect drug absorption, distribution, metabolism, and excretion (such as grapefruit-containing drinks) within 2 days prior to D-1 ；

• Pregnant or lactating women;

• Not suitable for this study as determined by the investigator due to other reasons.