Drug evaluation: OPT-80, a narrow-spectrum macrocyclic antibiotic.

Optimer Pharmaceuticals Inc, in collaboration with Par Pharmaceutical Companies Inc, is developing OPT-80, a narrow-spectrum macrocyclic antibiotic secreted by the actinomycete Dactylosporangium aurantiacum, for the potential treatment of Clostridium difficile-associated diarrhea (CDAD) and vancomycin-resistant Enterococcus infection. A phase IIb/III clinical trial of OPT-80 in patients with CDAD is underway.