ANX-015 is a proprietary intravenous formulation of an approved antibiotic in the macrolide family known as clarithromycin. Clarithromycin is highly potent against a variety of aerobic and anaerobic Gram-positive and Gram-negative organisms, such as in upper and lower respiratory tract infections. Clarithromycin is not available in the US in an intravenous (IV) formulation. Worldwide sales of IV clarithromycin exceeded 1.9 million units in 2005 (source: IMS Health). Injection site reactions, characterized by phlebitis and inflammation, may occur with IV clarithromycin.