Dosing & Uses
Dosage Forms & Strengths
capsule
- 250mg
- 500mg
Candidiasis/Cryptococcus Infection
Adjust dose for renal dysfunction
Other Indications & Uses
Off-label: chromomycosis
Interactions
Interaction Checker
No Results
Contraindicated
Serious - Use Alternative
Significant - Monitor Closely
Minor
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.
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
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
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.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)
Images
| BRAND | FORM. | UNIT PRICE | PILL IMAGE |
|---|---|---|---|
| Ancobon oral - | 500 mg capsule |  | |
| Ancobon oral - | 250 mg capsule |  | |
| 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 |  |
Copyright © 2010 First DataBank, Inc.
Patient Handout
flucytosine oral
FLUCYTOSINE - ORAL
(flew-SYE-toe-seen)
COMMON BRAND NAME(S): Ancobon
WARNING: This medication should be used with increased caution if you have kidney problems. Flucytosine may cause decreased kidney function and liver problems. In addition, this medication may decrease bone marrow function. This serious, possibly life-threatening side effect may lead to a low number of blood cells such as red cells, white cells, and platelets. This effect can cause anemia, decrease your body's ability to fight an infection, and cause bleeding problems. Your doctor will check the results of your kidney, liver, and blood tests and adjust your treatment to reduce your risk for these side effects. See also Side Effects section.
USES: Flucytosine is used to treat serious fungal infections in the body. It belongs to a class of drugs known as antifungal drugs. It is often used with other medications. It works by slowing the growth of certain types of fungus.
HOW TO USE: Take this medication by mouth as directed by your doctor, usually 4 times a day (every 6 hours). To reduce stomach upset, do not swallow all of the capsules for one dose at the same time. It may be best to swallow the capsules for each dose over a 15-minute period until the full dose is taken.The dosage is based on your medical condition, weight, and response to treatment.This medication works best when the amount of drug in your body is kept at a constant level. Take this drug at evenly spaced intervals. To help you remember, take it at the same times each day.Continue to take this medication until the full prescribed amount is finished, even if symptoms disappear after a few days. Stopping the medication too early may allow the fungus to continue to grow, which may result in a return of the infection.Tell your doctor right away if your condition lasts or gets worse.
SIDE EFFECTS: Nausea, vomiting, or diarrhea may occur. See the How to Use section about how to reduce stomach upset. If any of these effects last or get worse, tell your doctor or pharmacist promptly.Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.Tell your doctor right away if you have any serious side effects, including: signs of kidney problems (such as change in the amount of urine), signs of liver problems (such as nausea/vomiting that doesn't stop, stomach/abdominal pain, dark urine, yellowing eyes/skin), signs of anemia (such as unusual tiredness, fast breathing, pale skin, fast heartbeat), signs of infection (such as sore throat that doesn't go away, fever, chills, cough), signs of bleeding (such as easy bruising/bleeding, nose bleeds, bleeding gums, bloody/black/tarry stools, vomit that looks like coffee grounds), muscle weakness/cramping.A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
PRECAUTIONS: Before taking flucytosine, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.Before using this medication, tell your doctor or pharmacist your medical history, especially of: kidney problems, liver problems, decreased bone marrow function (low white, red or platelet blood counts), a certain metabolic disorder (DPD enzyme deficiency), radiation treatment, mineral imbalance (such as low level of potassium in the blood).Flucytosine can make you more likely to get infections or may make current infections worse. Stay away from anyone who has an infection that may easily spread (such as chickenpox, COVID-19, measles, flu). Talk to your doctor if you have been exposed to an infection or for more details.Tell your health care professional that you are using flucytosine before having any immunizations/vaccinations. Avoid contact with people who have recently received live vaccines (such as flu vaccine inhaled through the nose).To lower the chance of getting cut, bruised, or injured, use caution with sharp objects like razors and nail cutters, and avoid activities such as contact sports.During pregnancy, this medication should be used only when clearly needed. This medication is not recommended for use during the first 3 months of pregnancy. It may harm an unborn baby. Discuss the risks and benefits with your doctor.It is unknown if this drug passes into breast milk. Because of the possible risk to the infant, breast-feeding while using this drug is not recommended. Consult your doctor before breast-feeding.
DRUG INTERACTIONS: Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.Some products that may interact with this drug are: cytarabine, other drugs that may affect the kidneys (including NSAIDs such as ibuprofen or naproxen), other drugs that decrease bone marrow function or lower your number of blood cells or weaken the immune system (such as cancer chemotherapy, trimethoprim/sulfamethoxazole).This medication may interfere with certain laboratory tests (including serum creatinine), possibly causing false test results. Make sure laboratory personnel and all your doctors know you use this drug.
OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.
NOTES: Do not share this medication with others.Lab and/or medical tests (such as kidney/liver function, blood cell counts, blood mineral levels) should be done while you are taking this medication. Keep all medical and lab appointments. Consult your doctor for more details.
MISSED DOSE: If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.
STORAGE: Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.
Information last revised March 2023. Copyright(c) 2023 First Databank, Inc.
IMPORTANT: HOW TO USE THIS INFORMATION: This is a summary and does NOT have all possible information about this product. This information does not assure that this product is safe, effective, or appropriate for you. This information is not individual medical advice and does not substitute for the advice of your health care professional. Always ask your health care professional for complete information about this product and your specific health needs.
Formulary
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