This study plans to set up 5 dose groups across 7 cohorts, including intravenous bolus plus infusion administration as well as intravenous bolus alone. The study plans to enroll 8 participants per cohort (investigational drug: placebo = 6:2), including both males and females, totaling 56 healthy participants. The study begins with dose-escalation enrollment starting from Cohort 1. Each cohort receives a single dose, sequentially completing Cohorts 2, 3, 4, 5, 6, and 7. After each cohort's dosing is completed, a 7-day observation period is conducted for safety evaluation. If the termination criteria are not met, the study may proceed to the next dose level following assessment by the Safety Review Committee. By collecting adverse events, as well as abnormal indicators from vital signs, electrocardiograms, and laboratory tests, and collecting blood samples at planned time points to measure SIM0811 plasma concentration and thrombotic molecular markers, the study aims to evaluate the tolerability and safety of SIM0811 injection in Chinese healthy adult participants, characterize its pharmacokinetic profile after single-dose administration, and explore the change curves of thrombotic molecular markers (plasmin-α2 antiplasmin complex PIC, fibrin degradation products FDP)
Healthy Chinese male or female adults aged 18 to 45 years (inclusive), not pregnant and not breastfeeding.
Male participants weight ≥50 kg, female participants weight ≥45 kg, all ≤90 kg. Body Mass Index (BMI) between 19 and 26 kg/m² (inclusive). BMI = weight (kg) / height² (m²).
Female participants must avoid the menstrual period during the trial. participants of childbearing potential must commit to no plan for pregnancy, sperm/egg donation within 2 weeks before screening and for 6 months after the last dose, and voluntarily adopt highly effective contraception (including partner).
Able to complete the study according to protocol requirements and commit to abstaining from smoking and alcohol during the trial.
History of drug allergy, or specific allergies (asthma, urticaria, eczema, etc.), or allergic constitution (e.g., allergy to two or more drugs, foods, pollen), or known allergy or significant intolerance to the investigational product or any of its components.
Presence of clinically significant history of cardiovascular, respiratory, endocrine, urinary, digestive, hematological, neurological, skin, malignant tumor, infectious diseases, psychiatric disorders (e.g., seizures), metabolic abnormalities/dysfunction, etc.
Screening physical examination, vital signs, laboratory tests, or other examination results judged by the clinician as abnormal with clinical significance (confirmed upon repeat assessment); OR presence of the following abnormal laboratory indicators: Alanine aminotransferase (ALT), Aspartate aminotransferase (AST), total bilirubin, direct bilirubin, creatinine above the upper limit of normal (ULN); platelet count below the lower limit of normal (LLN); hyperkalemia, hypokalemia, hypercalcemia, or hypocalcemia judged by the investigator as abnormal and clinically significant; PT prolongation > ULN + 3s, TT prolongation > ULN + 3s, APTT prolongation > ULN + 10s, INR > 1.2, FIB < 1.5 g/L or > 4.0 g/L, D-Dimer above ULN.
Screening ECG findings judged as abnormal with clinical significance. Resting heart rate not within the range of 50 to 100 beats per minute (exclusive of boundaries). QTcF interval > 470 ms (QTcF = QT/(RR)^0.33) or PR interval outside the range of 120 to 220 ms.