Nick who observes thickening and discoloration of the nail of the index finger is most likely suffering from a fungal infection. Nail fungal infection is also known as onychomycosis or tinea unguium and is caused by many different types of fungi (yeasts or molds) . This infection cause the nail to become discolored, thick, and more likely to crack and break.
Well I cannot actually see any reasons,so I might as well just give my own.A drug might not recieve FDA approval because they need to find the good chemicals and the bad chemicals in the drug.If they find any bad chemicals in the drug,they will not approve it.Hope this helps!!!!
