Before any study-specific procedures begin, the study staff will review the Informed Consent Form to provide a detailed explanation of this clinical research study and its potential risks and benefits. The doctor and study staff will answer any questions. After receiving this information, if you wish to participate in the study, you will be required to sign an informed consent form.

In total, this study will involve 4 visits to the study center over a period of about 3 to 7 weeks. After consent has been given, the screening period of the study begins. During the screening visit, the study staff reviews medical history and conducts a series of study-related examinations and assessments to see if the study requirements are met. The screening visit can occur from 3 to 35 days before the 2^nd study visit.

Those participants who are determined to satisfy all study requirements will return to the study center for 2 treatment visits. This is a blinded clinical research study which means that qualified participants have a 50% chance, like flipping a coin, of receiving either PH94B or placebo. After these visits, there will be 1 follow-up visit for assessments and a safety check. These 3 visits will be about 1 week apart.