Initial studies have used a powder in capsule formulation of PH797804. In future studies an immediate release tablet will be used. The purpose of this study is to compare blood levels of PH797804 following an oral dose of the powder in capsule formulation and the tablet formulation. In addition the effect of food blood levels of PH797804 will be investigated

Inclusion Criteria:

• Healthy male or female subjects aged 21 to 55 years
• Healthy is defined as no clinical relevant abnormalities identified by a detailed medical history, full physical examination including blood pressure and pulse rate measurement, 12-lead ECG and clinical laboratory tests
• Willing to use acceptable methods of contraception as outlined in the study protocol
• Body mass index between 18 to 30 kg/m2
• Subjects who are willing and able to comply with the scheduled visits, treatment plan and other study procedures

Exclusion Criteria:

• Subjects with evidence or history of clinically significant disease
• Pregnant or nursing females
• Females of childbearing potential who are unwilling or unable to use an acceptable method of nonhormonal contraception from at least 14 days prior to the first dose until day 15 of period 4
• Subjects with conditions possibly affecting drug absorption (eg gastrectomy)
• A positive approved immunoassay/ELISA blood test for TB
• Subjects with a history of regular alcohol consumption exceeding 14 drinks/week for females or 21 drinks/week for men
• Subjects who have use prescription or nonprescription drugs, vitamins and/or dietary supplements within 7 days or 5 half-lives (whichever is longer) prior to the first dose of study medication
• Subjects who have been administered medications capable of inducing hepatic enzyme metabolism (eg barbiturates, rifampin, carbamazepine, phenytoin or primidone) within 14 days (or 5 half-lives of the inducing agent, whichever is longer) of day 1 or within 28 days of administration of St John's wort