Fidaxomicin (Dificid), a Novel Oral Macrocyclic Antibacterial Agent For the Treatment of Clostridium difficile-Associated Diarrhea in Adults.

INTRODUCTION As its name suggests, Clostridium difficile–associated diarrhea (CDAD) is a common infection caused by the toxinproducing bacterium C. difficile. The infection can result in inflammation and cellular damage in the colon, leading to potentially severe complications, including enterocolitis with toxic megacolon, and possible death.1–3 CDAD accounts for more than $1.1 billion in health care costs each year in the U.S.3–6 The disease is usually associated with antimicrobial exposure, gastrointestinal (GI) surgery, advanced age, a compromised immune system, and long stays in health care settings, among other risk factors (Table 1).5,7–9 Between 1999 and 2004, the mortality rate associated with CDAD increased from 5.7 to 23.7 deaths per 1 million people in the U.S.10 Individuals become infected if they touch items or surfaces contaminated with the bacteria or spores and then touch their mouths.5 For decades, therapies for CDAD have been studied in numerous comparative randomized trials, but current treatment losporangium aurantiacum. Fidaxomicin is not effective for systemic infections because of its minimal absorption.17 The drug’s chemical name is Oxacyclooctadeca-3,5,9,13,15-pentaen-2-one, 3[[[6-deoxy-4-O-(3,5-dichloro-2-ethyl-4,6dihydroxybenzoyl)-2-O-methyl-β-D-mannopyranosyl]oxy]methyl]-12-[[6-deoxy5-C-methyl-4-O-(2-methyl-1-oxopropyl)β-D-lyxo-hexopyranosyl]oxy]-11-ethyl-8hydroxy-18-[(1R)-1-hydroxyethyl]-9,13,1 5-trimethyl-,(3E,5E,8S,9E,11S,12R,13E, 15E,18S). Figure 1 illustrates the drug’s structural formula. Fidaxomicin is available in white to offwhite film-coated, oblong tablets. The inactive ingredients are microcrystalline cellulose, pregelatinized starch, hydroxypropyl cellulose, butylated hydroxytoluene, sodium starch glycolate, magnesium stearate, polyvinyl alcohol, titanium dioxide, talc, polyethylene glycol, and lecithin (soy).17