flucytosine (Rx)

Brand and Other Names:Ancobon, 5-FC, more...5-fluorocytosine
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Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

capsule

  • 250mg
  • 500mg

Candidiasis/Cryptococcus Infection

50-150 mg/kg/d div q6hr PO  

Adjust dose for renal dysfunction

Other Indications & Uses

Off-label: chromomycosis

Dosage Forms & Strengths

capsule

  • 250mg
  • 500mg

Candidiasis/Cryptococcus Infection

Child: same as adult dosing; 50-150 mg/kg/d div q6hr PO  

Neonates (<28 days old): 80-160 mg/kg/d div q6hr PO

Adjust dose for renal dysfunction

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Interactions

Interaction Checker

and flucytosine

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     activity indicator 
    No Interactions Found
    Interactions Found

    Contraindicated

      Serious - Use Alternative

        Significant - Monitor Closely

          Minor

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             activity indicator 

            Contraindicated (0)

              Serious - Use Alternative (4)

              • bacitracin

                flucytosine and bacitracin both increase nephrotoxicity and/or ototoxicity. Avoid or Use Alternate Drug. Avoid concurrent use of bacitracin with other nephrotoxic drugs

              • deferiprone

                deferiprone, flucytosine. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Avoid use of deferiprone with other drugs known to be associated with neutropenia or agranulocytosis; if an alternative is not possible, monitor absolute neutrophil count more frequently.

              • ropeginterferon alfa 2b

                ropeginterferon alfa 2b, flucytosine. Either increases toxicity of the other by Other (see comment). Avoid or Use Alternate Drug. Comment: Myelosuppressive agents can produce additive myelosuppression. Avoid use and monitor patients receiving the combination for effects of excessive myelosuppression.

              • Saccharomyces boulardii

                flucytosine decreases effects of Saccharomyces boulardii by unspecified interaction mechanism. Avoid or Use Alternate Drug. Systemic or oral antifungals may decrease activity of probiotic.

              Monitor Closely (8)

              • dichlorphenamide

                dichlorphenamide and flucytosine both decrease serum potassium. Use Caution/Monitor.

              • hydroxyurea

                flucytosine, hydroxyurea. Other (see comment). Use Caution/Monitor. Comment: Combination may increase risk of myelosuppression.

              • ifosfamide

                ifosfamide, flucytosine. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Ifosfamide may enhance the toxicities of myelosuppressive agents. Monitor for increased risk of myelosuppression.

              • lomustine

                lomustine, flucytosine. Either increases toxicity of the other by pharmacodynamic synergism. Use Caution/Monitor. Coadministration may increase risk of myelosuppressive effects.

              • peramivir

                flucytosine increases levels of peramivir by decreasing renal clearance. Use Caution/Monitor. Caution when peramivir coadministered with nephrotoxic drugs.

              • tenofovir DF

                flucytosine, tenofovir DF. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Use Caution/Monitor.

                flucytosine increases levels of tenofovir DF by decreasing renal clearance. Use Caution/Monitor.

              • tobramycin inhaled

                tobramycin inhaled and flucytosine both increase nephrotoxicity and/or ototoxicity. Modify Therapy/Monitor Closely. Avoid concurrent or sequential use to decrease risk for ototoxicity

              • voclosporin

                voclosporin, flucytosine. Either increases toxicity of the other by nephrotoxicity and/or ototoxicity. Modify Therapy/Monitor Closely. Coadministration with drugs associated with nephrotoxicity may increase the risk for acute and/or chronic nephrotoxicity.

              Minor (6)

              • amphotericin B deoxycholate

                flucytosine increases effects of amphotericin B deoxycholate by pharmacodynamic synergism. Minor/Significance Unknown.

                amphotericin B deoxycholate increases levels of flucytosine by decreasing elimination. Minor/Significance Unknown.

              • fluconazole

                flucytosine increases effects of fluconazole by pharmacodynamic synergism. Minor/Significance Unknown.

              • ganciclovir

                ganciclovir increases toxicity of flucytosine by pharmacodynamic synergism. Minor/Significance Unknown.

              • itraconazole

                flucytosine increases effects of itraconazole by pharmacodynamic synergism. Minor/Significance Unknown.

              • valganciclovir

                valganciclovir increases toxicity of flucytosine by pharmacodynamic synergism. Minor/Significance Unknown.

              • zidovudine

                zidovudine increases toxicity of flucytosine by pharmacodynamic synergism. Minor/Significance Unknown.

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              Adverse Effects

              Frequency Not Defined

              Confusion

              Headache

              Hallucinations

              Dizziness

              Drowsiness

              Psychosis

              Parkinsonism

              Ataxia

              Sedation

              Rash

              Photosensitivity

              Pruritus

              Urticaria

              Temporary growth failure

              Hypoglycemia

              Hypokalemia

              Nausea

              Vomiting

              Diarrhea

              Abdominal pain

              Loss of appetite

              Bone marrow suppression

              Anemia

              Leukopenia

              Thrombocytopenia

              Elevated liver enzymes

              Hepatitis

              Azotemia

              Peripheral neuropathy

              Paresthesia

              Weakness

              Hearing loss

              Elevated BUN and serum creatinine

              Renal failure

              Respiratory arrest

              Anaphylaxis

              Postmarketing Reports

              To report suspected adverse reactions, contact Bausch Health US, LLC at 1-800-321- 4576 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch

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              Warnings

              Black Box Warnings

              Use extreme caution in patients with renal impairment

              Monitor hematologic, renal, and hepatic function

              Review instructions thoroughly before administration

              Contraindications

              Hypersensitivity

              Patients with known complete dihydropyrimidine dehydrogenase (DPD) enzyme deficiency

              Cautions

              Measurement of serum creatinine levels should be determined by Jaffé reaction since this drug does not interfere with determination of creatinine values by this method; most automated equipment for measurement of creatinine makes use of the Jaffé reaction

              Electrolytes (because of hypokalemia), hematologic, and renal status of the patient should be determined before therapy instituted; close monitoring of patient during therapy is essential.

              Use extreme caution in patients with impaired renal function; monitor blood concentrations and kidney function in renal impairment; drug can progressively accumulate; dosage adjustments should be made in patients with renal insufficiency to prevent progressive accumulation of active drug

              Bone marrow depression

              • Administer with extreme caution to patients with bone marrow depression; patients maybe more prone to depression of bone marrow function if they have a hematologic disease or are being treated with radiation, treated with drugs which depress bone marrow, or have a history of treatment with such drugs or radiation
              • Bone marrow toxicity can be irreversible and may lead to death in immunosuppressed patients; frequent monitoring of hepatic function and of the hematopoietic system indicated during therapy

              Dihydropyrimidine dehydrogenase deficiency

              • 5-Fluorouracil is a metabolite of flucytosine; dihydropyrimidine dehydrogenase is a key enzyme involved in the metabolism and elimination of 5-fluorouracil; the risk of severe drug toxicity is increased when drug used in individuals with deficiency in DPD
              • Possible drug toxicitiesinclude mucositis, diarrhea, neutropenia, and neurotoxicity; determination of DPD activity may be considered where drug toxicity is confirmed or suspected; in the event of suspected drug toxicity, consider stopping treatment

              Drug interaction overview

              • Cytosine arabinoside, a cytostatic agent, reported to inactivate the antifungal activity of this drug by competitive inhibition; drugs that impair glomerular filtration may prolong biological half-life of flucytosine
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              Pregnancy & Lactation

              Pregnancy

              Flucytosine was shown to be teratogenic (vertebral fusions) in the rat at doses of 40 mg/kg/day(298 mg/m2/day or 0.051 times the human dose) administered on days 7 to 13 of gestation

              At higher doses (700 mg/kg/day; 5208 mg/m2/day or 0.89 times the human dose administered on days 9 to 12 of gestation), cleft lip and palate and micrognathia reported

              This drug was not teratogenic in rabbits up to a dose of 100 mg/kg/day (1423 mg/m2/day or 0.243 times human dose) administered on days 6 to 18 of gestation

              In mice, 400 mg/kg/day of flucytosine (1380 mg/M2/day or 0.236 times the human dose) administered on days 7 to 13 of gestation was associated with low incidence of cleft palate that was not statistically significant

              Studies in pregnant rats have shown that flucytosine injected intraperitoneally crosses the placental barrier; there are no adequate and well-controlled studies in pregnant women; this drug should be used during pregnancy only if the potential benefit justifies potential risk to fetus

              Lactation

              Not known whether this drug is excreted in human milk; because many drugs are excreted in human milk and because of potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother

              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

              Competitive inhibition of purine, pyrimidine uptake

              Pharmacokinetics

              Absorption: 75-90%

              Distribution: into CSF, aqueous humor, joints, peritoneal fluid, & bronchial secretions

              Protein Bound: 2-4%

              Half-life elimination: 3-8 hr; anuria: up to 200 hr; end-stage renal disease: 75-200 hr

              Peak Plasma Time: 2-6 hr

              Metabolism: minimally hepatic

              Excretion: urine (75-90% as unchanged drug)

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              Images

              BRAND FORM. UNIT PRICE PILL IMAGE
              flucytosine oral
              -
              500 mg capsule
              flucytosine oral
              -
              250 mg capsule
              flucytosine oral
              -
              250 mg capsule
              flucytosine oral
              -
              500 mg capsule
              flucytosine oral
              -
              250 mg capsule
              flucytosine oral
              -
              500 mg capsule
              flucytosine oral
              -
              500 mg capsule
              flucytosine oral
              -
              250 mg capsule
              Ancobon oral
              -
              500 mg capsule
              Ancobon oral
              -
              250 mg capsule

              Copyright © 2010 First DataBank, Inc.

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              Formulary

              FormularyPatient Discounts

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              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.
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              Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the 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.