3. Subjects must be generally healthy, with the exception of AD but may be enrolled with a stable, chronic illness, if it is well controlled and does not interfere with the primary objective of the study. Subjects may be included with clinically important deviations from normal limits in medical history, physical examination findings, vital sign measurements, findings on 12 lead electrocardiogram (ECG), or chronic laboratory test results that are associated with stable, well controlled chronic illness.