This is an open-label, single-dose, two period crossover study to evaluate the effect of food on the bioavailability of the To-Be-Marketed Formulation of CTP-543 in Healthy Volunteers

Inclusion Criteria:

• Healthy, adult, male or female, 18-60 years of age, inclusive
• Nonsmoker who has not used nicotine containing products for at least 3 months
• Body mass index (BMI) ≥ 18.0 and ≤ 32.0 kg/m2 at screening
• Medically healthy with no clinically significant medical history, physical examination, laboratory profiles, vital signs, or ECGs
• If of reproductive age, willing and able to use a medically highly effective form of birth control 4 weeks prior to first dose, during the study and for 30 days following last dose of study medication
• Capable of giving informed consent and complying with study procedures.

Exclusion Criteria:

• History or presence of clinically significant medical or psychiatric condition or disease
• History of any illness that might confound the results of the study or poses an additional risk to the subject by their participation in the study
• History or presence of alcohol or drug abuse within the past 2 years
• Presence or history of significant gastrointestinal, liver or kidney disease, or any other condition that is known to interfere with drug absorption, distribution, metabolism or excretion, or known to potentiate or predispose to undesired effects
• History of prolonged QT syndrome or a QTc interval with Fridericia's correction (QTcF) > 450 msec for males or QTcF > 470 msec for females
• Abnormal liver function at screening
• Females who are nursing, pregnant, or planning to become pregnant while in the study, and for 30 days after last dose of study drug
• Positive results for coronavirus infection (COVID-19) at screening or check-in (Day -1)
• Positive drug or alcohol results at screening
• Positive results at screening for human immunodeficiency virus (HIV), hepatitis B surface antigen (HBsAg) or hepatitis C virus (HCV)
• Participation in another clinical study within 30 days prior to, and 30 days after the first dosing