DUSA Pharmaceuticals, Inc. is a pharmaceutical company developing drugs in combination with light devices to treat or detect a variety of conditions in processes known as photodynamic therapy or photodetection. The Company is engaged primarily in the research, development and marketing of its first drug, Levulan brand of aminolevulinic acid HCl (ALA), for use in a range of medical conditions. When the Company uses Levulan and follows it with exposure to light to treat a medical condition, it is known as Levulan photodynamic therapy (Levulan PDT). When it uses Levulan and follows it with exposure to light to detect medical conditions, it is known as Levulan photodetection (Levulan PD). In September 2003, the Company received clearance from the United States Food and Drug Association (FDA) to market the BLU-U, without Levulan PDT, for the treatment of moderate inflammatory acne vulgaris.