General

Pronunciation:
fi-dax-oh-mye-sin

Trade Name(s)

• Dificid

Ther. Class.
anti-infectives

Pharm. Class.
macrolides

Indications

Treatment of diarrhea associated with Clostridioides difficile.

Action

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

Therapeutic Effect(s):

Elimination of diarrhea caused by Clostridioides difficile.

Pharmacokinetics

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

Contraindication/Precautions

Contraindicated in:

• Hypersensitivity to fidaxomicin or macrolides (cross-sensitivity may occur).

Use Cautiously in:

• OB:   Use during pregnancy only if potential maternal benefit justifies potential fetal risk;
• Lactation: Use while breastfeeding only if potential maternal benefit justifies potential risk to infant;
• Pedi:   Children <6 mo (safety and effectiveness not established).

Adverse Reactions/Side Effects

GI: GI HEMORRHAGE, nausea, abdominal pain

Hemat: anemia, neutropenia

Misc: HYPERSENSITIVITY REACTIONS (INCLUDING ANGIOEDEMA)

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

Interactions

Drug-Drug

None reported.

Route/Dosage

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

PO (Children ≥6 mo and ≥12.5 kg): Tablets– 200 mg twice daily for 10 days (if unable to swallow tablets, use granules for oral suspension).

PO (Children ≥6 mo and 9–<12.5 kg): Granules for oral suspension– 160 mg twice daily for 10 days.

PO (Children ≥6 mo and 7–<9 kg): Granules for oral suspension– 120 mg twice daily for 10 days.

PO (Children ≥6 mo and 4–<7 kg): Granules for oral suspension– 80 mg twice daily for 10 days.

Availability

Granules for oral suspension (berry-flavor): 200 mg/5 mL

Tablets: 200 mg

Assessment

• 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

• Risk for infection (Indications) 
• Diarrhea (Indications) 

Implementation

• PO 

  Administer twice daily, about 12 hr apart, without regard to food.

  • For oral suspension, shake the glass bottle to ensure the granules move around freely and no caking has occurred. Measure 130 mL of purified water, add to glass bottle, and cap tightly. Hold bottle in a horizontal position and shake bottle vigorously in that position for at least 2 minutes. Verify that suspension is homogeneous; shake again. Once suspension is homogeneous, shake an additional 30 seconds. Let bottle stand for 1 min. Verify that suspension is still homogeneous. If not, repeat previous steps. Once reconstituted, oral suspension is white to yellowish white. Write discard date (current date plus 12 days) on the bottle. Stable in refrigerator for up to 12 days; discard after 12 days. Remove bottle from refrigerator 15 min before administration. Shake vigorously until suspension is homogenous. Administer orally with or without food using an oral dosing syringe to ensure accurate dose.

Patient/Family Teaching

• Instruct patient to take fidamoxicin twice daily, 12 hr apart, 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 patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult with health care professional before taking other medications.
• Advise females of reproductive potential to notify health care professional if pregnancy is planned or suspected or if breast feeding.

Evaluation/Desired Outcomes

Decrease in diarrhea caused by Clostridioides difficile.