Senicapoc is being developed by Icagen Inc as a novel treatment of the symptoms of atopic (allergic) asthma. Atopic asthma is an increasingly common disease. Data from the Centers for Disease Control and Prevention estimates that 7.7% or 22 million people in the United States suffer from asthma. Atopic asthma is essentially caused by an allergic reaction of the immune system. When a human body encounters an allergen, the immune system responds by releasing various cells into the airways in order to fight these foreign particles. However, in an asthmatic patient the body response is exaggerated and the airways are excessively occupied by different types of cells that may or may not be helpful in fighting the allergen. One of these many cells is known as mast cell. Mast cells commonly play an important protective role in our immune system as they are involved in wound healing and defence against harmful foreign particles that enter our body. However, when present in excessive quantities as in an asthmatic patient, these cells tend to cause harm by stimulating the excessive release of products which constrict the airways. Senicapoc may work by blocking specific protein channels on the mast cells and dampen mast cell responses. This study will take place in up to 3 clinical research units and will involve approximately 30 volunteers. For each subject the study will usually involve three screening visits (the second visit may involve an overnight stay in the unit), a two week dosing period with visits to the unit on Days 1, 4, 13 (may involve an overnight stay in the unit) and 14. There will also be two follow up visits.