This trial is a Phase I, single-center, randomized, double-blind, placebo-controlled study conducted in healthy Chinese adult subjects.

The purpose of this study is to learn about:

• Safety and tolerability of PRT-064040 nasal spray in healthy adult subjects.
• Pharmacokinetics after single and multiple dose of PRT-064040 nasal spray in healthy Chinese adult subjects.

This study is divided into two parts:

• Eligible subjects in Part A will receive a single dose of PRT-064040 nasal spray or placebo.
• Eligible subjects in Part B will receive multiple doses of PRT-064040 nasal spray or placebo, administered once daily (QD) for a total of 7 consecutive days.

Inclusion Criteria:

1. Healthy male or female Chinese adults aged ≥18 years and ≤55 years.
2. Body Mass Index of 18 to 28 kg/m^2; and a total body weight ≥50 kg for males and ≥45 kg for females.

Exclusion Criteria:

1. History of allergy to any medications, foods, or other substances.
2. History or presence of any severe diseases that are considered clinically significant by the investigator.
3. Any clinically significant abnormal laboratory test results or positive test.
4. Any nasal conditions or diseases that, in the investigator's judgment, may significantly affect the administration or absorption of a nasal product.
5. Standard 12-Lead Electrocardiogram that demonstrates clinically relevant abnormalities.
6. Pregnant or breastfeeding women, or those with a positive pregnancy test result during screening.
7. Positive urine drug screen, alcohol breath test, or nicotine test.
8. History of significant alcohol abuse or drug abuse.
9. Donation or loss of blood of approximately 400 mL or more within 3 months prior to dosing.
10. Previous participation in another clinical trial and receiving the investigational drug within 3 months prior to dosing.