Bioequivalence Study of GZR18 Injection Before and After CMC Change

This is an open-label, randomized, single-dose, parallel comparison bioequivalence study conducted in healthy adult male subjects. The study is divided into 3 parts, each of which evaluates the bioequivalence of GZR18 Injection for one strength before and after CMC changes. Subjects eligible for each part of the screening will be randomized into Group A or Group B in a 1:1 ratio. Each subject will receive a single dose of GZR18 Injection, followed by PK blood sampling and safety follow-up for 35 days. Subjects will be admitted to the hospital 1 day predose, follow a standardized light diet that evening, and then fast for at least 10 h thereafter. On the day of administration, GZR18 Injection of a single strength will be administered subcutaneously under fasting conditions at a site approximately two finger-widths (2.5 cm) away from the umbilicus on the abdomen. Lunch and dinner will be served approximately 3 and 9 h postdose, respectively. Venous blood will be collected at 14 time points for GZR18 plasma concentration analysis: at 0 h (within 60 min predose) and 1, 6, 24, 48, 72, 96, 120, 168, 240, 336, 504, 672, and 840 h postdose. Subjects will undergo corresponding laboratory safety tests at screening, D36, and early withdrawal visits. During the entire study period, subjects should maintain a light diet, avoid strenuous exercise, and refrain from consuming juice, caffeinated beverages (such as tea and coffee), and alcoholic drinks. Smoking and any other activities that may affect PK observation or safety evaluations are strictly prohibited.