A Single Dose Study To Test Two Pediatric Forms Of Ritlecitinib Compared With Adult Ritlecitinib In Healthy Adults

Inclusion Criteria: * Male and female participants who are healthy as determined by medical evaluation including a detailed medical history, complete (full) physical examination, which includes BP and pulse rate measurement, clinical laboratory tests, and 12-lead ECG. * BMI of 17.5 to 30.5 kg/m2; and a total body weight \>50 kg (110 lb). Exclusion Criteria: * Evidence or history of clinically significant hematological, renal, endocrine, pulmonary, gastrointestinal, cardiovascular, hepatic, psychiatric, neurological, dermatological, or allergic disease (including drug allergies, but excluding untreated, asymptomatic, seasonal allergies at the time of dosing). * Any condition possibly affecting drug absorption (eg, gastrectomy, cholecystectomy). * Known immunodeficiency disorder, including positive serology for HIV at screening, or a first degree relative with a hereditary immunodeficiency * Infection with hepatitis B or hepatitis C viruses. * History of any lymphoproliferative disorder * Known present or a history of malignancy other than a successfully treated or excised nonmetastatic basal cell or squamous cell cancer of the skin or cervical carcinoma in situ