Prior to administering PF-04427429 to patients we wish to increase the understanding of functional effects associated with calcitonin gene related peptide (CGRP) pathways. This study will examine whether it is possible for a single dose of PF-04427429 to acutely attenuate a capsaicin induced flare response.

Proof of mechanism in healthy volunteers

Inclusion Criteria:

• Healthy male subjects between the ages of 18 and 50 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.
• Evidence of a personally signed and dated informed consent document indicating that the subject (or a legally acceptable representative) has been informed of all pertinent aspects of the trial.
• Skintype I-III with a distance from base of scaphoid to antecubital fossa >26cm on their forearms.

Exclusion Criteria:

• Evidence or history of clinically significant hematological, renal, endocrine, pulmonary, gastrointestinal, cardiovascular, genitourinary, psychiatric, neurologic, or allergic disease (including drug allergies, but excluding untreated, symptomatic, seasonal allergies at time of dosing).
• Use of biologics including any live vaccines within 3 months prior to screening or prior treatment with an antibody in a previous clinical trial or treatment with an immunoglobulin in the past 6 months.
• 12-lead ECG demonstrating QTcF >450 msec at screening.
• Subjects with scars or tattoos on the forearms, or with evidence of sunburn, or excessive hairy volar forearms.