The most notable tolerability finding from these multiple dosing studies has been the occurrence of mild to moderate rash at doses of 450 mg BID and 600 mg BID. Based upon this finding, the current four week study is designed to examine whether a slow titration regimen up to a lower maintenance dose of 450 mg BID is able to reduce the incidence of rash.

Inclusion Criteria:

• Healthy male and/or female subjects of non-child bearing 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

Exclusion Criteria:

• Evidence or history of clinically significant hematological, renal (ie, recurrent nephrolitisis), endocrine, pulmonary, gastrointestinal, cardiovascular, hepatic, psychiatric, neurologic, or allergic disease (including drug allergies, but excluding untreated, asymptomatic, seasonal allergies at time of dosing).
• History of, or presence of allergic skin reactions or active skin disease (except for subjects with acne who may be included in the study) at the time of screening.