The purpose of this First In Human study is to investigate the safety and tolerability of KL1333 after a single oral dose and to investigate the pharmacokinetic characteristics of KL1333 after a single oral dose.

Inclusion Criteria:

• 19 - 45 years of age at the time of screening
• Subjects weighing ≥55 and ≤90 kg with BMI between 18 and 27 kg/m2
• Subjects who agreed to voluntarily participate in this study and comply with all the study requirements by signing informed consent form after being informed of the nature of this study and understanding all aspects of this study

Exclusion Criteria:

• History of clinically significant hepatic, renal, neurologic, immunologic, respiratory, endocrine disease or hematologic•oncologic disease, cardiovascular, psychiatric disease
• History of disease or surgery of the gastrointestinal tract that could interfere with kinetics of the study drug. Simple hernia repair or appendectomy are excepted.
• History of clinically significant or relevant allergy/hypersensitivity
• Blood AST (SGOT), ALT (SGPT) >1.5 of upper limit
• eGFR value of ≤90mL/min/1.73m2
• Systolic blood pressure of <100 mmHg or >160 mmHg
• Diastolic blood pressure of <60 mmHg or >100 mmHg
• Any abnormalities in 12-lead ECG at screening visit
• Subjects who showed positive result in drug abuse tests, or who has history of drug abuse within 60 days prior to the time of screening
• Subjects who took prescribed medications or oriental medicine within 14 days or over-the-counter (OTC) medications or vitamins within 7 days prior to the dose of the study drug (however, the subject can be included if other criteria are met according to the discretion of the investigator)
• Subjects who were administered any investigational products within 3 months from the first dose of the study drug
• Subjects who have donated whole blood (60 days) or partial blood (30 days), or received blood transfusion
• Subjects who have had alcohol consistently (>21units/week, 1unit=10 g of pure alcohol) or who is not able to stop drinking alcohol throughout the study period
• Subjects who have smoked until 90 days prior to the study initiation or who are not able to stop smoking throughout the study period
• Subjects who are not able to stop taking grapefruit/caffeine from 3 days prior to the first dose of the study drug throughout the study period
• Subjects who plan for pregnancy during the study period or who are not able to use established contraceptive method
• Subject who judged not eligible for study participation by investigator