A Study to Demonstrate the Equivalence of the Tofacitinib Oral Solution to the Tablet Formulation in Healthy Participants.

• Tofacitinib tablet (Drug): Single dose of tofacitinib 5 mg tablet
• Tofacitinib Oral Solution (Drug): Single 5 mL dose of tofacitinib oral solution (1 mg/mL)

Primary outcomes

• AUCinf for tofacitinib oral solution and tofacitinib tablet [24 hrs after study drug administration in Period 1 and Period 2]: Area under the curve from time zero to extrapolated infinite time for both oral solution and tofacitinib.
• AUClast for tofacitinib oral solution and tofacitinib tablet [24 hrs after study drug administration in Period 1 and Period 2]: Area under the plasma concentration time curve from 0 to time of the last measurement of both the tofacitinib oral solution and tofacitinib tablet.

Secondary outcomes

• Cmax for tofacitinib oral solution and tofacitinib tablet [24 hrs after study drug administration in Period 1 and Period 2]: Maximum observed plasma concentration for tofacitinib oral solution and tofacitinib tablet
• Number of subjects with adverse events (AEs). [Screening to up to 28-35 days after the last dose of study medication in Period 2.]: Number of subjects with adverse events (AEs).
• Number of subjects with laboratory tests findings of potential clinical importance [Screening through Day 2 of Period 2]: Number of subjects with laboratory tests findings of potential clinical importance
• Number of subjects with clinically significant abnormal vital signs [Screening through Day 2 of Period 2]: Number of subjects with clinically significant abnormal vital signs
• Number of subjects with clinically significant physical examination findings [Screening to Day 2 of Period 2]: Number of subjects with clinically significant physical examination findings.

Sex: All, ages: 18 Years to 55 Years, accepts healthy volunteers

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.

• Results publication: Chang C, Vong C, Wang X, Hazra A, Diehl A, Nicholas T, Mukherjee A. Tofacitinib pharmacokinetics in children and adolescents with juvenile idiopathic arthritis. CPT Pharmacometrics Syst Pharmacol. 2024 Apr;13(4):599-611. doi: 10.1002/psp4.13104. Epub 2024 Jan 31. PMID 38298058

• Pfizer CT.gov Call Center, Study director, Pfizer