| Interventions |
Part 1 (Single Ascending Dose) Lowest starting dose of 50 mg RS1805 tablets, and the dose level will be gradually escalated. The maximum dose in the single ascending-dose part is planned to be 600 mg RS1805 tablets administered orally. The intervention drug will be administered once only. It is planned to enroll 40 healthy adult subjects in Australia. Part 1 includes a total of 5 cohorts. There are 8 subjects in each cohort, including 6 subjects in the study drug (RS1805 tablets) group and 2 subjects in the placebo group, male or female subjects. The first cohort is randomized to receive 50 mg RS1805 tablets or placebo in a 3:1 ratio. The second cohort is randomized to receive 100 mg RS1805 tablets or placebo in a 3:1 ratio. The third cohort is randomized to receive 200 mg RS1805 tablets or placebo in a 3:1 ratio. The fourth cohort is randomized to receive 400 mg RS1805 tablets or placebo in a 3:1 ratio. The fifth cohort is randomized to receive 600 mg RS1805 tablets or placebo in a 3:1 ratio Part 2 (Multiple Ascending Dose) Starting dose of 100 mg RS1805 tablets, and the dose level will be gradually escalated. The maximum dose in the multiple ascending-dose part is planned to be 400 mg RS1805 tablets administered orally. The intervention drug will be administered daily for 7 days. It is planned to enroll 24 healthy adult subjects in Australia. Part 2 includes a total of 3 cohorts. There are 8 subjects in each cohort, including 6 subjects in the study drug (RS1805 tablets) group and 2 subjects in the placebo group, male or female subjects. The first cohort is randomized to receive 100 mg (tentative, to be confirmed after review of Part 1 data) RS1805 tablets or placebo in a 3:1 ratio. The second cohort is randomized to receive 200 mg (tentative, to be confi |