fidaxomicin (Rx)

Brand and Other Names:Dificid
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Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

tablet

  • 200mg

Clostridioides difficile-Associated Diarrhea

Indicated for treatment of Clostridioides difficile-associated diarrhea (CDAD)

200 mg PO BID x10 days

Dosage Modifications

Renal impairment

  • Dose adjustment not necessary

Hepatic impairment

  • Not studied; dose adjustment not necessary since minimally absorbed

Dosing Considerations

To reduce the development of drug-resistant bacteria and maintain the effectiveness, use only to treat infections that are proven or strongly suspected to be caused by C difficile

Dosage Forms & Strengths

tablet

  • 200mg

oral granules for suspension

  • 200mg/5mL (40mg/mL) after reconstitution

Clostridioides difficile-Associated Diarrhea

Indicated for treatment of Clostridioides difficile-associated diarrhea (CDAD) infection in pediatric patients aged ≥6 months

<6 months: Safety and efficacy not established

6 months or older

  • Tablets
    • ≥12.5 kg: 200 mg PO BID x10 days
  • Oral suspension
    • Weight base dose x10 days
    • 4 to <7 kg: 80 mg PO BID
    • 7 to <9 kg: 120 mg PO BID
    • 9 to <12.5 kg: 160 mg PO BID
    • ≥12.5 kg: 200 mg PO BID

Dosing Considerations

To reduce the development of drug-resistant bacteria and maintain the effectiveness, use only to treat infections that are proven or strongly suspected to be caused by C difficile

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Adverse Effects

>10% (Adults)

Nausea (11%)

>10% (Pediatrics)

Pyrexia (13.3%)

1-10% (Adults)

Vomiting (7%)

Abdominal pain (6%)

Gastrointestinal hemorrhage (4%)

Anemia (2%)

Neutropenia (2%)

<2%

  • Gastrointestinal disorders: Abdominal distension, abdominal tenderness, dyspepsia, dysphagia, flatulence, intestinal obstruction, megacolon
  • Investigations: Increased blood alkaline phosphatase, decreased blood bicarbonate, increased hepatic enzymes, decreased platelet count
  • Metabolism and nutrition disorders: Hyperglycemia, metabolic acidosis
  • Skin and subcutaneous tissue disorders: Drug eruption, pruritus, rash

1-10% (Pediatrics)

Abdominal pain (8.2%)

Vomiting (7.1%)

Diarrhea (7.1%)

Constipation (5.1%)

Increased AST/ALT (5.1%)

Rash (5.1%)

Postmarketing Reports

Hypersensitivity reactions (dyspnea, angioedema, rash, pruritus)

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Warnings

Contraindications

Hypersensitivity

Cautions

Not indicated for systemic infections owing to minimal systemic absorption

Only use for infection proven or strongly suspected to be caused by C difficile to avoid development of drug resistant bacteria; therapy not effective for treatment of other types of infections due to minimal systemic absorption of fidaxomicin

Acute hypersensitivity reactions, including dyspnea, rash, pruritus, and angioedema of the mouth, throat, and face reported; discontinue and treat appropriately if reaction occurs therapy should be instituted

Some patients with hypersensitivity reactions also reported a history of allergy to other macrolides

Use in the absence of proven or strongly suspected C difficile infection is unlikely to provide benefit to the patient and increases risk of developing drug-resistant bacteria

Drug interaction overview

  • Not dependent on CYP450 enzymes for metabolism
  • Fidaxomicin and its main metabolite, OP-1118, are P-gp substrates, but not significantly affected by P-gp inhibitors
  • Based on results of studies coadministered with cyclosporine, fidaxomicin may be co-administered with P-gp inhibitors and no dose adjustment is recommended
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Pregnancy & Lactation

Pregnancy

Limited available data in pregnant women are insufficient to inform any drug-associated risk for major birth defects; miscarriage or adverse maternal or fetal outcomes

Animal data

  • Embryo-fetal reproduction studies in rats and rabbits dosed intravenously during organogenesis revealed no evidence of harm to fetus at exposures 65-fold or higher than the clinical exposure at the recommended dose

Lactation

There is no information on presence of fidaxomicin or its main metabolite, OP-1118, in human milk, the effects on breastfed infant, or on milk production; developmental and health benefits of breastfeeding should be considered along with mother’s clinical need for therapy and any potential adverse effects on breastfed infant from therapy or from the underlying maternal condition

Pregnancy Categories

A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

NA: Information not available.

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Pharmacology

Mechanism of Action

Macrolide antibiotic that inhibits RNA synthesis by binding to RNA polymerases

Bactericidal against C difficile in vitro; demonstrates a postantibiotic effect vs C difficile of 6-10 hr

Absorption

Bioavailability: Minimal systemic absorption

Peak plasma time: 2 hr (range 1-5 hr)

Peak plasma concentration: 5.2 ng/mL (+/- 2.81)

AUC: 14 ng•hr/mL

Distribution

Fecal concentrations: 639-2710 mcg/g; OP-1118 213-1210 mcg/g

Metabolism

Metabolized by hydrolysis at the isobutyryl ester to form OP-1118

Metabolites: OP-1118 (active metabolite)

Elimination

Half-life: 9 hr

Excretion: Feces (92%)

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Administration

Oral Suspension Preparation

Shake glass bottle to ensure 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 horizontal position and shake bottle vigorously in that position for at least 2 minutes

Verify homogeneous suspension obtained; if not, repeat shaking

Once homogeneous suspension is visually confirmed, shake an additional 30 seconds

Let bottle stand for 1 minute

Verify that the suspension is still homogeneous; if not, repeat shaking instructions

Once reconstituted, oral suspension is white to yellowish white in color

Write discard date (current date plus 12 days) on the bottle

Oral Administration

May take with or without food

Oral suspension

  • Remove bottle from refrigerator 15 minutes before administration
  • Shake vigorously until suspension has an even consistency
  • Remove cap, then administer orally with or without food using an oral dosing syringe
  • Between doses, replace cap and refrigerate

Storage

Tablets

  • 20-25ºC (68-77ºF); excursions permitted to 15-30ºC (59-86ºF)
  • Store in the original bottle

Oral suspension

  • Unreconstituted granules
    • 20-25ºC (68-77ºF); excursions permitted to 15-30ºC (59-86ºF)
    • Store in the original package; do not open pouch until time of use
  • Reconstituted suspension
    • Refrigerate at 36-46ºF (2-8ºC) for up to 12 days
    • Store capped in the original bottle
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Images

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Formulary

FormularyPatient Discounts

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The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

Tier Description
1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
NC NOT COVERED – Drugs that are not covered by the plan.
Code Definition
PA Prior Authorization
Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
QL Quantity Limits
Drugs that have quantity limits associated with each prescription. This restriction typically limits the quantity of the drug that will be covered.
ST Step Therapy
Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
OR Other Restrictions
Drugs that have restrictions other than prior authorization, quantity limits, and step therapy associated with each prescription.
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Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.