Beijing Zhuokai Biotechnology Co., Ltd.

Primary objective: To evaluate the safety and tolerability of 50561 tablets in the treatment of patients with mild to moderate AD. Secondary objectives: To evaluate the preliminary efficacy of 50561 tablets in the treatment of patients with mild to moderate AD; Based on the population pharmacokinetic (PopPK) analysis method, evaluate the pharmacokinetic (PK) characteristics of 50561 and its major metabolites (if applicable) in patients with mild to moderate AD; If data permit, preliminarily evaluate the correlation between the exposure of 50561 and its major metabolites (if applicable) and efficacy and adverse events (AEs). Other objectives: If data permit, preliminarily evaluate the exposure of 50561 and its major metabolites (if applicable) in cerebrospinal fluid to evaluate the blood-brain barrier permeability of 50561; Evaluate the pharmacodynamic (PD) characteristics of 50561 in patients with mild to moderate AD.

To evaluate the preliminary efficacy, safety and tolerability of different doses of 50561 tablets compared with placebo in the treatment of patients with mild to moderate AD, and to evaluate the PK and PD characteristics of 50561 and its major metabolites (if applicable) in patients with mild to moderate AD.

Primary objective: To evaluate the safety and tolerability of 50561 tablets after multiple oral administration in healthy Chinese adult subjects. Secondary objective: To evaluate the pharmacokinetic (PK) characteristics of 50561 tablets after multiple oral administration in healthy Chinese adult subjects. Other objectives: To evaluate the types of possible metabolites of 50561 in plasma and the PK characteristics of the main metabolites (if applicable).