This drug-drug interaction (DDI) study has been designed to characterize the pharmacokinetic profile of SHR8554 when co administered with a strong cytochrome P450 3A4 (CYP3A4) inhibitor itraconazole

Inclusion Criteria:

1. Healthy male and female subjects, aged 18 to 45 years (inclusive).
2. Female subjects body weight≥45 kg, male subjects body weight≥50 kg, body mass index (BMI) of 19.0 to 26.0 kg/m2 (inclusive).
3. Understand the study procedures in the informed consent form and be willing and able to comply with the protocol.

Exclusion Criteria:

1. Subjects with a history of drug allergy, or a history of specific allergies, or known allergy to SHR8554 or itraconazole or similar.
2. Any condition or disease detected during the medical interview/physical examination that would render the participant unsuitable for the study as determined by the investigator.
3. Subjects with positive tests for infectious diseases.
4. Subjects who have undergone major surgery within 3 months prior to screening or have undergone surgery that could significantly affect the in vivo course or safety evaluation of the study drug.
5. History of using any medication within 2 weeks prior to the first dosing.
6. Subjects who have received vaccination within 1 month prior to screening or plan to receive vaccination during the trial.
7. Excessive daily consumption of tea, coffee, grapefruit/grapefruit juice and other special diets in the 1 month prior to screening.
8. Subjects with a history of substance abuse, drug use or a positive screening test for substance abuse.
9. Female who are pregnant or breastfeeding, or have a positive pregnancy test.
10. Subjects who may not be able to complete the study for other reasons or who the investigator believes should not be included.