Pharmacologic class: Macrolide

Therapeutic class: Anti-infective

Pregnancy risk category B


Bactericidal against Clostridium difficile in vitro, inhibiting RNA synthesis by RNA polymerases


Tablets: 200 mg

Indications and dosages

C. difficile-associated diarrhea

Adults: 200-mg tablet P.O. b.i.d. for 10 days




Use cautiously in:

• systemic infections or absence of proven or strongly suspected C. difficile infection

• pregnant or breastfeeding patients

• children younger than age 18 (safety and efficacy not established).


• Administer with or without food.

• Be aware that using drug in absence of proven or strongly suspected C. difficile infection is unlikely to provide benefit to patient and increases risk of development of drug-resistant bacteria.

• Be aware that drug has minimal systemic absorption and isn't effective in treatment of systemic infections.

Adverse reactions

GI: nausea, vomiting, abdominal pain, GI hemorrhage

Hematologic: anemia, neutropenia


Drug-drug. Cyclosporine: increased plasma concentrations of fidaxomicin and its metabolite

Patient monitoring

• Monitor CBC periodically.

• Observe patient for signs and symptoms of GI hemorrhage.

Patient teaching

• Tell patient to take drug with or without food.

• Inform patient that drug only treats C. difficile-associated diarrhea and shouldn't be used to treat other infections.

• Inform patient that although it's common to feel better early in the course of therapy, the drug should be taken exactly as directed. Skipping doses or not completing full course of therapy may decrease effectiveness of immediate treatment and increase likelihood that bacteria will develop resistance and won't be treatable by this drug or other antibacterials in the future.

Instruct patient to promptly report signs and symptoms of GI bleeding.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs mentioned above.


(fi-dax-oh-mye-sin) ,


(trade name)


Therapeutic: anti infectives
Pharmacologic: macrolides
Pregnancy Category: B


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 effects

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.

Time/action profile



Contraindicated in: Hypersensitivity.
Use Cautiously in: Obstetric / Lactation: Use during pregnancy only if clearly needed, use cautiously during lactation; Pediatric: Safe and effective use in children <18 yr has not been established.

Adverse Reactions/Side Effects


  • GI hemorrhage (life-threatening)
  • nausea (most frequent)
  • abdominal pain


  • anemia
  • neutropenia


  • hypersensitivity reactions (life-threatening)


Drug-Drug interaction

No significant interactions noted.


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


Tablets: 200 mg

Nursing implications

Nursing assessment

  • Monitor bowel function for diarrhea, abdominal cramping, fever, and bloody stools. May begin up to several weeks 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 Nursing Diagnoses

Risk for infection (Indications)
Diarrhea (Indications)


  • Oral: 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.
References in periodicals archive ?
UKPRwire, Tue Jan 30 2018] Global Fidaxomicin Market is expected to grow at a significant CAGR in the upcoming years as the scope and its applications are rising enormously across the globe.
SAN FRANCISCO--The role of fidaxomicin for treating mild to moderate Clostridium difficile infection is still finding its way, according to Sarah Doernberg, MD.
In the Phase 2 clinical trial, ridinilazole preserved the gut microbiome of CDI patients to a greater extent than the marketed narrow-spectrum antibiotic, fidaxomicin.
No information could be gathered regarding treatment with fidaxomicin since at present time its distribution is not approved in Mexico.
Treatment to date is generally with an even stronger antibiotic than prescribed for the initial illness, such as metronidazole, vancomycin, or fidaxomicin.
Clinical trial data support the use of vancomycin over metronidazole for those with initial Clostridium difficile infection, and fidaxomicin over vancomycin for the prevention of recurrent infection, according to a newly released update of the 2011 Agency for Healthcare Research and Quality Comparative Effectiveness Review.
Fidaxomicin (DIFICID), approved in Canada in 2012 for treatment of CDI, is an orally administered, minimally absorbed, bactericidalmacrocyclic antibiotic [27-30].
Scientists studying data on 1,071 patients from five NHS trusts found the antibiotic fidaxomicin reduced C.
When fidaxomicin was approved in 2011, it became the first new drug to tackle C.
A chronology of important events illustrates milestones in research, from the seventeenth-century discovery of microbes to the 2011 development of the antibiotic Fidaxomicin in Infectious Disease Research, while the 1953 discovery of DNA to the 2010 creation of the first synthetic organism bookend the chronology for Biotech Research.
This edition includes new drugs, including Azilsartan Medoxomil, Boceprevir, Clobazam, Ezogabine, Fidaxomicin, Linagliptin, Rilpivirine, Rivaroxaban, Telaprevir, Roflumilast, Ticagrelor, and Vilazodone; updated bisphosphonate, antipsychotic, carbapenem, and proton pump inhibitor group monographs; new combinations such as Emtricitabine/Rilpivirine/Tenofovir; and a revised ophthalmic/otic chapter with additions like glaucoma combinations, mast cell stabilizers, ophthalmic antihistamines, and otic corticosteroids.