This study is to compare and evaluate the safety and pharmacokinetic characteristics (PK) after administration of SID1903 and SID1903-R1/SID1903-R2 in healthy adult volunteers.

Inclusion Criteria:

• Healthy subjects aged between 19 years and 55 years(inclusive)
• Subjects weighing at least 50.0 kg and no more than 100 kg (inclusive) with a BMI between 18.5 kg/m2 and 30.0 kg/m2 (inclusive)
• Subjects with neither congenital nor chronic diseases requiring treatment, and no abnormal symptoms or findings upon medical examination
• Subjects considered eligible for the study participation in accordance to the results of vital signs, physical examinations, 12-lead ECG, clinical laboratory tests (including hematology, blood chemistry, urinalysis, serology, etc.) and urine drug screening conducted at the time of screening, based on the investigational product (IP) characteristics
• Subjects who has a full understanding in participation of the study, voluntarily provide a written consent in participation, and give full agreement in following the subject guidelines throughout the entire study period

Exclusion Criteria:

• Subjects with any clinically significant hepatic, renal, nervous, respiratory, endocrine, circulatory, genitourinary, cardiovascular, digestive, musculoskeletal systemic diseases, psychosis disorders, or other medical history
• Subjects with a past medical history of gastrointestinal disease or gastrointestinal surgeries
• Pregnant subjects with a positive urine HCG test, or lactating female subjects
• Subjects with hypersensitivity reactions or a clinically significant medical history of hypersensitivity reactions to drug substances and additives containing drug substances or other drugs
• Subjects with clinically significant 12-lead ECG findings
• Subjects with clinically significant laboratory test results as follows: Liver function test (AST, ALT, ALP, γ-GTP and total bilirubin), Creatinine, eGFR
• Subjects with a past history of drug abuse or a positive urine drug test
• Subjects with SBP ≥ 140 mmHg or ≤ 90 mmHg; DBP ≥ 90 mmHg or ≤ 60 mmHg; PR ≤ 50 beats/min or ≥ 100 beat/min
• Subjects following an unusual diet or consumption of food which may affect the absorption, distribution, metabolism and excretion of the IP
• Subjects taking drugs known to significantly induce or inhibit drug metabolizing enzymes, including barbitals prior to the first IP administration
• Subjects who have participated and were given any other study drugs in other clinical study within 6 months prior to the first IP administration
• Subjects who have consistently drunk alcohol within 6 months
• Subjects who have smoked more than 10 cigarettes/day on average
• Subjects who have done and are unable to refrain from strenuous activity
• Subjects who are planning for pregnancy or not willing to use a medically reliable forms of contraception
• Subjects otherwise considered ineligible for participation due to other reasons including clinical laboratory test results not mentioned in the inclusion/exclusion criteria at the investigator's discretion