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Fidaxomicin(trade names Dificid, Dificlir, and previously OPT-80 and PAR-101) is the first in a new class of narrow spectrum macrocyclic antibiotic drugs. It is a fermentation product obtained from the actinomycete ''Dactylosporangium aurantiacum subspecies hamdenesis''.〔(【引用サイトリンク】url=http://www.dificid.com/upload/dificid.pdf )〕 Fidaxomicin is non-systemic, meaning it is minimally absorbed into the bloodstream, it is bactericidal, and it has demonstrated selective eradication of pathogenic ''Clostridium difficile'' with minimal disruption to the multiple species of bacteria that make up the normal, healthy intestinal flora. The maintenance of normal physiological conditions in the colon can reduce the probability of ''Clostridium difficile'' infection recurrence. It is marketed by Cubist Pharmaceuticals after acquisition of its originating company Optimer Pharmaceuticals. The target use is for treatment of ''Clostridium difficile'' infection. Fidaxomicin is available in a 200 mg tablet that is administered every 12 hours for a recommended duration of 10 days. Total duration of therapy should be determined by the patient's clinical status. It is currently one of the most expensive antibiotics approved for use. A standard course costs upwards of £1350.〔http://www.medicinescomplete.com/mc/bnf/current/PHP18388-dificlir.htm#PHP18388-dificlir〕 ==Mechanism== Fidaxomicin binds to and prevents movement of the "switch regions" of bacterial RNAP polymerase. Switch motion is important for opening and closing of the DNA:RNA clamp, a process that occurs throughout RNA transcription but especially during opening of double standed DNA during transcription initiation. It has minimal systemic absorption and a narrow spectrum of activity; it is active against Gram positive bacteria especially clostridia. The minimal inhibitory concentration (MIC) range for ''C. difficile'' (ATCC 700057) is 0.03–0.25 μg/mL.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「fidaxomicin」の詳細全文を読む スポンサード リンク
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