This is a Phase 1, randomized, open label, 2 period, 2 sequence, cross over, single dose study to evaluate the AUC equivalence, and safety of tofacitinib 5 mL oral solution (1 mg/mL) and 5 mg tablet in healthy participants. Participants will be randomized to 1 of the 2 treatment sequences. A total of approximately 12 healthy male and/or female (non-childbearing potential) participants will be enrolled in the study so that approximately 6 participants will be enrolled in each treatment sequence. Each treatment sequence will consist of 2 periods. In both sequences, participants will remain in the CRU for a total of 5 days and 4 nights (including Period 1 and Period 2).

Inclusion Criteria:

• Male and female participants of non childbearing potential must be 18 to 55 years of age, inclusive, at the time of signing the informed consent document (ICD).
• Male and female participants of non-childbearing potential who are overtly healthy as determined by medical evaluation including medical history, physical examination, laboratory tests, blood pressure (BP), pulse rate, oral temperature, and 12 lead electrocardiogram (ECG).
• Body mass index (BMI) of 17.5 to 30.5 kg/m^2; and a total body weight greater than 50 kg (110 lb).

Exclusion Criteria:

• Evidence or history of clinically significant hematological, renal, endocrine, pulmonary, gastrointestinal, cardiovascular, hepatic (including alcoholic liver disease, nonalcoholic steatohepatitis (NASH), autoimmune hepatitis, and hereditary liver diseases), psychiatric, neurological, or allergic disease (including drug allergies, but excluding untreated, asymptomatic, seasonal allergies at the time of dosing).
• Clinically significant infections within the past 3 months prior to the baseline visit (for example, those requiring hospitalization or parenteral antibiotics, or as judged by the investigator), evidence of any infection within the past 7 days prior to the baseline visit, history of disseminated herpes simplex infection or recurrent (>1 episode) herpes zoster or disseminated herpes zoster.
• Any condition possibly affecting drug absorption (eg, gastrectomy).
• History of human immunodeficiency virus (HIV) infection, hepatitis B, or hepatitis C; positive testing for HIV, hepatitis B surface antigen (HBsAg), hepatitis B core antibody (HBcAb), or hepatitis C antibody (HCVAb). Hepatitis B vaccination is allowed.
• Malignancy or a history of malignancy, with the exception of adequately treated or excised non metastatic basal cell or squamous cell cancer of the skin or cervical carcinoma in situ.
• A positive urine drug test.

Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical\_trials/trial\_data\_and\_results/data\_requests.