Cethromycin
Cethromycin is a 3-keto (ketolide) derivative of erythromycin A with an 11,12-carbamate group and an O-6-linked aromatic ring system. Cethromycin represents a joint development effort by Abbott Laboratories, Taisho Pharmaceuticals, and Advanced Life Sciences, intended to be marketed under the trade name Restanza for the treatment of community-acquired pneumonia. However, after completing phase III clinical trials, it was deemed safe but not sufficiently efficacious by the FDA.  Since this time, cethromycin has received FDA orphan drug designations for the prophylactic treatment of anthrax inhalation, plague due to Yersinia pestis, and tularemia due to Francisella tularensis. It has also been investigated, by itself or together with [zoliflodacin], for the treatment of gonorrhea, and was recently suggested as a possible treatment for liver-stage Plasmodium sporozoite infection.