This study is testing a new medicine called LAD603 in healthy adults to see if it's safe and how the body handles it. It's in two parts. Part 1 checks single doses, and Part 2 checks multiple doses. **Pharmacokinetics (PK)** is how the body absorbs and gets rid of the drug, and **pharmacodynamics (PD)** looks at how the drug affects the body. The study lasts about 8 weeks for Part 1 and 14 weeks for Part 2. Participants should be between 18 and 65 years old and in good health. They should not have serious illnesses or be pregnant. Some participants will be given different doses in groups, and the dose can change based on safety. The study checks blood pressure, heart rate, and other health markers. Participants must not smoke or use drugs.

• **Duration:** 8 weeks (Part 1) or 14 weeks (Part 2)
• **Eligibility:** Healthy adults aged 18-65
• **Compensation:** Not specified, but will include health check-ups