Phase I PK and Safety Study of Ondansetron Inhalation Powder

The goal of this clinical trial is to learn if LPI-1503 (Ondansetron Inhalation Powder) can deliver ondansetron into blood through inhalation. It will also learn about the safety of LPI-1503. The main questions it aims to answer are: Does ondansetron enter into blood after inhalation of LPI-1503? And if it does, how efficiently? how rapidly? What medical problems do participants have when and after inhaling LPI-1503? Researchers will compare LPI-1503 to a placebo (a look-alike substance that contains no drug), and to orally swallowed and injected administrated ondansetron. Participants will: Visit site and take LPI-1503 or a placebo once by inhalation, followed by checkups and tests; and (if took LPI-1503 in visit 1) After one week, visit site again to take ondansetron by orally swallowing or by injection, followed by checkups and tests.