A Study Comparing the Pharmacokinetics and Safety of Different Vitamin C Doses in Healthy Adults

INTERVENTION: Drug : Participants will be randomized 1:1:1 to three dose groups. Under fasting conditions, they will receive a single oral dose of vitamin C 1,000 mg (one Yuhan Vitamin C 1000 mg tablet), 2,000 mg (two tablets), or 4,000 mg (four tablets) with 150 mL of water. All groups are open‐label and single‐dose, with pharmacokinetic and safety assessments through 8 hours after dosing. CONDITION: Factors influencing health status and contact with health services PRIMARY OUTCOME: AUClast and Cmax of vitamin C and oxidized vitamin C SECONDARY OUTCOME: AUCinf, Tmax, t1/2, CL/F, and Vd/F of vitamin C and oxidized vitamin C Safety assessments: vital signs, adverse events, physical examinations, and laboratory tests INCLUSION CRITERIA: 1. Healthy adults aged 19 to 55 years at screening. 2. Body mass inde Xof 17.5 to 30.5 kg/m² and body weight of at least 45 kg. 3. No congenital or chronic disease within the previous 3 years and no pathological symptoms or findings on medical examination. 4. Judged eligible based on hematology, blood chemistry, urinalysis, and other screening examinations. 5. Women must have a confirmed negative pregnancy status and agree to maintain contraception until 2 weeks after the final investigational product dose, excluding hormone‐containing contraceptive devices and oral contraceptives. 6. Voluntarily agrees to participate after receiving adequate information about the purpose and procedures and signs an IRB‐approved written informed consent form.