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Trade Name(s)

  • Dificid

Ther. Class.

Pharm. Class.


Treatment of diarrhea associated with Clostridium difficile.


  • Bactericial action mostly against clostridia; inhibits RNA synthesis.
  • Acts locally in the GI tract to eliminate Clostridium difficile.

Therapeutic Effect(s):

Elimination of diarrhea caused by Clostridium difficile.


Absorption: Minimal systemic absorption.

Distribution: Stays primarily in the GI tract.

Metabolism and Excretion: Mostly transformed via hydrolysis in the GI tract to OP-1118, its active metabolite. Eliminated mostly (>92%) in feces: <1% excreted in urine.

Half-life: Fidaxomicin– 11.7 hr; OP-1118– 11.2 hr.




Contraindicated in:

  • Hypersensitivity.

Use Cautiously in:

  • OB: Lactation:Use during pregnancy only if clearly needed, use cautiously during lactation;
  • Pedi: Safe and effective use in children <18 yr has not been established.

Adverse Reactions/Side Effects

GI: GI HEMORRHAGE, nausea, abdominal pain

Hemat: anemia, neutropenia


* CAPITALS indicate life-threatening.
Underline indicate most frequent.



No significant interactions noted.


PO: (Adults >18 yr): 200 mg twice daily for 10 days.


Tablets: 200 mg


  • Monitor bowel function for diarrhea, abdominal cramping, fever, and bloody stools. May begin up to several wk following cessation of antibiotic therapy.
  • Monitor for signs and symptoms of hypersensitivity reactions (dyspnea, pruritus, rash, angioedema of mouth, throat, and face) periodically during therapy. Risk increases with a macrolide allergy.

Lab Test Considerations: May cause ↑ serum alkaline phosphatase, and hepatic enzymes.

  • May cause ↓ serum bicarbonate, ↓ platelet count, anemia, and neutropenia.
  • May cause hyperglycemia and metabolic acidosis.

Potential Diagnoses


  • PO: Administer twice daily without regard to food.

Patient/Family Teaching

  • Instruct patient to take fidamoxicin as directed for the full course of therapy, even if feeling better. Skipping doses or not completing full course of therapy may decrease effectiveness of therapy and increase risk that bacteria will develop resistance and not be treatable in the future.
  • Advise female patients to notify health care professional if pregnancy is planned or suspected or if breast feeding.

Evaluation/Desired Outcomes

Decrease in diarrhea caused by Clostridium difficile.

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Quiring, Courtney, et al. "Fidaxomicin." Davis's Drug Guide, 16th ed., F.A. Davis Company, 2019. Medicine Central, im.unboundmedicine.com/medicine/view/Davis-Drug-Guide/109605/all/fidaxomicin.
Quiring C, Sanoski CA, Vallerand AH. Fidaxomicin. Davis's Drug Guide. 16th ed. F.A. Davis Company; 2019. https://im.unboundmedicine.com/medicine/view/Davis-Drug-Guide/109605/all/fidaxomicin. Accessed April 21, 2019.
Quiring, C., Sanoski, C. A., & Vallerand, A. H. (2019). Fidaxomicin. In Davis's Drug Guide. Available from https://im.unboundmedicine.com/medicine/view/Davis-Drug-Guide/109605/all/fidaxomicin
Quiring C, Sanoski CA, Vallerand AH. Fidaxomicin [Internet]. In: Davis's Drug Guide. F.A. Davis Company; 2019. [cited 2019 April 21]. Available from: https://im.unboundmedicine.com/medicine/view/Davis-Drug-Guide/109605/all/fidaxomicin.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - fidaxomicin ID - 109605 A1 - Quiring,Courtney, AU - Sanoski,Cynthia A, AU - Vallerand,April Hazard, BT - Davis's Drug Guide UR - https://im.unboundmedicine.com/medicine/view/Davis-Drug-Guide/109605/all/fidaxomicin PB - F.A. Davis Company ET - 16 DB - Medicine Central DP - Unbound Medicine ER -