This study was terminated on January 6, 2010, due to toxicology findings in animals exposed to PF-04455242 for three months.

This is a subject blind, investigator and sponsor open, randomized study consisting of 2 parts. Up to 15 healthy subjects will be included in the study. In the first part of the study the test retest reliability of the radiotracer [11C] PF 04767135 binding in man will be assessed. In the second part of this study, using [11C] PF 04767135, kappa opioid receptor occupancy (RO) will be assessed in up to three cohorts of subjects.

Inclusion Criteria:

• Healthy male and/or female subjects of non-childbearing potential between the ages of 18 and 55 years, inclusive. (Healthy is defined as no clinically 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.)

Exclusion Criteria:

• Evidence or history of clinically significant hematological, renal, endocrine, pulmonary, gastrointestinal, cardiovascular, hepatic, psychiatric, neurologic, or allergic disease (including drug allergies, but excluding untreated, asymptomatic, seasonal allergies at time of dosing).
• Any condition possibly affecting drug absorption (eg, gastrectomy).
• A positive urine drug screen at Screening or Day 0.
• History of regular alcohol consumption exceeding 7 drinks/week for females or 14 drinks/week for men.
• Use of tobacco- or nicotine-containing products within 3 months of screening.
• Treatment with an investigational drug within 30 days or 5 half lives preceding the first dose of study medication (excluding [11C]PF 04767135).
• 12 lead ECG demonstrating QTc >450 msec at Screening.
• Pregnant or nursing females; females of childbearing potential.