Antifungal p.4
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Questions and Answers

What is the recommended dosing range for clients with normal renal function who are taking flucytosine?

  • 50 - 150 mg/kg/day (correct)
  • 25 - 75 mg/kg/day
  • 100 - 200 mg/kg/day
  • 150 - 250 mg/kg/day

    • Which of the following drugs is known to have a potential risk of nephrotoxicity when combined with flucytosine?

  • Quinidine
  • Amphotericin B (correct)
  • Cisapride
  • Pimozide

    • In clients with renal insufficiency, what action must be taken regarding flucytosine dosing?

  • Administer off-label dosages
  • Increase the dosage
  • Reduce the dosage (correct)
  • Keep the dosage the same

    • Which tests should be monitored weekly in clients taking flucytosine?

    <p>Liver Function Tests (LFTs)</p> Signup and view all the answers

    What is the primary risk associated with the concomitant use of flucytosine and certain antiarrhythmics?

    <p>Fatal dysrhythmias</p> Signup and view all the answers

    What is the primary function of flucytosine?

    <p>It serves as a narrow-spectrum antifungal agent.</p> Signup and view all the answers

    Which of the following fungi is flucytosine most effective against?

    <p>Candida species</p> Signup and view all the answers

    What is a unique feature of flucytosine's use in therapy?

    <p>It is almost always used in combination with amphotericin B.</p> Signup and view all the answers

    How does flucytosine exert its antifungal effects?

    <p>By being converted into 5-fluorouracil in fungal cells.</p> Signup and view all the answers

    What is the most severe complication associated with flucytosine therapy?

    <p>Bone marrow suppression</p> Signup and view all the answers

    In which patients should caution be exercised when administering flucytosine?

    <p>Patients with renal impairment.</p> Signup and view all the answers

    What is a common side effect of flucytosine?

    <p>Mild and reversible hepatic dysfunction</p> Signup and view all the answers

    Which enzyme is absent in human cells that makes flucytosine relatively harmless to them?

    <p>Cytosine deaminase</p> Signup and view all the answers

    What is the main reason flucytosine is used in combination with amphotericin B?

    <p>To prevent the development of resistance</p> Signup and view all the answers

    Which of the following best describes the mechanism of action of flucytosine?

    <p>It disrupts DNA and RNA synthesis</p> Signup and view all the answers

    Flucytosine is primarily indicated for which type of infections?

    <p>Systemic fungal infections</p> Signup and view all the answers

    What is a common side effect associated with flucytosine therapy?

    <p>Bone marrow suppression</p> Signup and view all the answers

    Which enzyme is responsible for converting flucytosine to its active form that is harmful to fungi?

    <p>Cytosine deaminase</p> Signup and view all the answers

    What is the risk associated with prolonging flucytosine therapy in patients with renal impairment?

    <p>Accumulation leading to toxicity</p> Signup and view all the answers

    What is the typical half-life consideration for flucytosine in patients with renal impairment?

    <p>Prolonged half-life requiring dosage adjustment</p> Signup and view all the answers

    What aspect of flucytosine makes it relatively harmless to human cells?

    <p>Mammalian cells lack a specific enzyme that metabolizes flucytosine</p> Signup and view all the answers

    What is the significance of monitoring serum drug levels in clients taking flucytosine?

    <p>To avoid toxicity due to inadequate kidney function.</p> Signup and view all the answers

    What should be monitored weekly in clients taking flucytosine to assess for potential adverse effects?

    <p>Platelet and leukocyte counts.</p> Signup and view all the answers

    Why is extreme caution advised in clients with renal impairment taking flucytosine?

    <p>Flucytosine can accumulate, leading to toxicity.</p> Signup and view all the answers

    What is a potential consequence of using flucytosine with CYP450 inhibitors?

    <p>Elevated plasma levels of certain drugs.</p> Signup and view all the answers

    Which of the following statements about flucytosine dosing is true?

    <p>Dosing must be individualized based on client response.</p> Signup and view all the answers

    What aspect of flucytosine therapy necessitates careful monitoring in clients with existing hematologic disorders?

    <p>Risk of bone marrow suppression</p> Signup and view all the answers

    What is the correct dosing interval for flucytosine when administered at a dosing range of 50-150 mg/kg/day?

    <p>Every 4 hours</p> Signup and view all the answers

    Which laboratory tests are essential to monitor for hepatotoxicity in clients receiving flucytosine?

    <p>Liver Function Tests</p> Signup and view all the answers

    Why is it important to monitor renal function in clients receiving flucytosine?

    <p>To prevent flucytosine toxicity</p> Signup and view all the answers

    In clients taking flucytosine and certain antiarrhythmics, what is the primary risk associated with increased plasma levels?

    <p>Fatal dysrhythmias</p> Signup and view all the answers

    What is the primary reason flucytosine is almost always used in combination with amphotericin B?

    <p>To counteract commonly developed resistance</p> Signup and view all the answers

    Which of the following fungal infections is flucytosine indicated for treating?

    <p>Candidiasis</p> Signup and view all the answers

    Which side effect is most severe and associated with flucytosine therapy?

    <p>Bone marrow suppression</p> Signup and view all the answers

    What biochemical process does flucytosine disrupt in fungal cells?

    <p>DNA and RNA synthesis</p> Signup and view all the answers

    Flucytosine is relatively harmless to humans because human cells lack which of the following?

    <p>Cytosine deaminase</p> Signup and view all the answers

    What is a significant precaution to consider when prescribing flucytosine?

    <p>Use caution in clients with renal impairment</p> Signup and view all the answers

    What metabolite is formed when flucytosine is converted inside fungal cells?

    <p>5-fluorouracil</p> Signup and view all the answers

    Which of the following is considered a common side effect of flucytosine use?

    <p>Mild and reversible hepatic dysfunction</p> Signup and view all the answers

    What dosages should be used for clients with renal insufficiency taking flucytosine?

    <p>Doses must be reduced from standard recommendations</p> Signup and view all the answers

    Which laboratory test is crucial for monitoring potential hepatic damage in clients receiving flucytosine?

    <p>Liver Function Tests</p> Signup and view all the answers

    What is a significant risk when flucytosine is used alongside cisapride or quinidine?

    <p>Increased plasma levels leading to fatal dysrhythmias</p> Signup and view all the answers

    Why is extreme caution advised when administering flucytosine to clients with renal impairment?

    <p>Because it can accumulate and cause toxicity</p> Signup and view all the answers

    Which component of renal function must be monitored to ensure safe flucytosine treatment?

    <p>BUN and Creatinine levels</p> Signup and view all the answers

    Which adverse reaction is characterized by a significant risk during therapy with flucytosine?

    <p>Fatal agranulocytosis</p> Signup and view all the answers

    What mechanism primarily accounts for the antifungal activity of flucytosine?

    <p>Disruption of DNA and RNA synthesis</p> Signup and view all the answers

    Which of the following is most likely to develop resistance to flucytosine?

    <p>Candida krusei</p> Signup and view all the answers

    In addition to flucytosine, which antifungal agent is commonly used in combination to enhance therapeutic effectiveness?

    <p>Amphotericin B</p> Signup and view all the answers

    What is a notable characteristic of flucytosine's safety profile in humans?

    <p>Human cells do not convert flucytosine to 5-FU</p> Signup and view all the answers

    Which condition is the main reason for caution when prescribing flucytosine?

    <p>Renal impairment</p> Signup and view all the answers

    What should be closely monitored to prevent potential adverse effects associated with flucytosine use?

    <p>Liver enzyme levels</p> Signup and view all the answers

    Flucytosine displays the highest antifungal activity against which organism?

    <p>Cryptococcus neoformans</p> Signup and view all the answers

    Study Notes

    Flucytosine: Antifungal Agent

    • Category: Pyrimidine analog antifungal agent.
    • Primary Function: Narrow-spectrum antifungal agent, most effective against Candida and Cryptococcus neoformans.
    • Unique Feature: Often used in combination with amphotericin B due to common resistance development.
    • Mechanism of Action: Converted to 5-fluorouracil (5-FU) by fungal cells, interfering with DNA and RNA synthesis. Human cells are relatively unaffected due to lacking cytosine deaminase.

    Therapeutic Uses

    • Systemic Fungal Infections: Treats candidiasis and cryptococcosis, especially severe forms like systemic candidiasis and cryptococcal meningitis, often in combination with amphotericin B.

    Side Effects

    • Hematologic: Bone marrow suppression, reversible neutropenia or thrombocytopenia, rare risk of fatal agranulocytosis.
    • Hepatic: Mild and reversible hepatic dysfunction is common, severe injury is rare.

    Precautions & Contraindications

    • Renal Impairment: Use caution due to prolonged half-life, adjust dosage for renal insufficiency.
    • Hematologic Disorders: Use caution in clients with pre-existing hematologic disorders or bone marrow suppression.
    • Black Box Warning: Extreme caution in clients with renal impairment due to prolonged half-life.

    Drug Interactions

    • Amphotericin B: Can cause nephrotoxicity. Combined use requires adequate kidney function to prevent flucytosine toxicity.
    • Cisapride, Pimozide, Dofetilide, Quinidine: Flucytosine can inhibit CYP450 enzymes, increasing plasma levels of these drugs, posing a risk of fatal dysrhythmias.

    Dosing & Administration

    • Dosing: Varies based on condition, severity, and client response. Often combined therapy with amphotericin B.
    • Dosage: Flucytosine capsules (250mg & 500mg). For clients with normal renal function: 50-150mg/kg/day in four divided doses every 6 hours. Reduced dosage for renal insufficiency.
    • Administration: Oral administration.
    • Client Teaching: Monitor for hematologic and hepatic adverse effects.

    Labs to Monitor

    • Basic Metabolic Panel (BMP): Monitor renal function (BUN/Creatine, Creatine Clearance).
    • Complete Blood Count (CBC): Monitor platelet and leukocyte count weekly.
    • Liver Function Tests (LFTs): Monitor weekly for hepatotoxicity.
    • Serum Drug Levels: Monitor flucytosine levels in clients receiving concomitant amphotericin B therapy.

    Flucytosine - Pyrimidine Analog Antifungal

    • Flucytosine is a narrow-spectrum antifungal agent effective against susceptible strains of Candida and Cryptococcus neoformans.
    • Flucytosine is typically used in combination with amphotericin B due to the high risk of developing fungal resistance.
    • Flucytosine is taken up by fungal cells and converted to 5-fluorouracil (5-FU), which disrupts fungal DNA and RNA synthesis.
    • Human cells lack cytosine deaminase, preventing the conversion of flucytosine to 5-FU and rendering it relatively harmless to humans.

    Indications and Therapeutic Uses

    • Flucytosine is indicated for treating candidiasis and cryptococcosis.
    • For severe infections like systemic candidiasis and cryptococcal meningitis, flucytosine should be combined with amphotericin B.

    Side Effects and Adverse Reactions

    • Hematologic Effects: Bone marrow suppression is the most serious side effect, including reversible neutropenia or thrombocytopenia, and a rare risk of fatal agranulocytosis.
    • Hepatotoxicity: Mild and reversible hepatic dysfunction is common, but severe hepatic injury is rare.

    Precautions and Contraindications

    • Clients with renal impairment: Reduced dosage is required due to a prolonged half-life of flucytosine.
    • Clients with hematologic disorders and bone marrow suppression: Use with caution.

    Black Box Warning

    • Use with extreme caution in clients with renal impairment due to the prolonged half-life of flucytosine.

    Drug Interactions

    • Amphotericin B: Can cause nephrotoxicity, requiring adequate kidney function to prevent flucytosine toxicity.
    • Cisapride, pimozide, dofetilide, or quinidine: Concomitant use can increase their plasma levels, increasing the risk of fatal dysrhythmias.

    Dosing, Administration, & Client Teaching

    • Dosing: Varies based on the condition, severity, and client response.
    • Administration: Oral administration.
    • Client Teaching: Monitor for hematologic and hepatic adverse effects.

    Labs to Monitor

    • Basic Metabolic Panel (BMP): Monitor renal function (BUN/Creatinine and Creatine Clearance) during therapy.
    • Complete Blood Count (CBC): Monitor weekly for platelet and leukocyte counts.
    • Liver Function Tests (LFTs): Monitor weekly for hepatotoxicity.
    • Serum Drug Levels: Monitor flucytosine levels in clients concomitantly using amphotericin B.

    Overview of the Drug Class

    • Flucytosine is a narrow-spectrum antifungal agent in the Pyrimidine Analog Antifungal Agent category
    • It is primarily effective against Candida and Cryptococcus neoformans
    • Flucytosine is often used in combination with amphotericin B due to the high likelihood of developing resistance

    Mechanism of Action

    • Flucytosine is taken up by fungal cells and converted into 5-fluorouracil (5-FU)
    • 5-FU disrupts fungal DNA and RNA synthesis
    • Mammalian cells lack the enzyme, cytosine deaminase, which converts flucytosine to 5-FU making flucytosine relatively safe for humans

    Indications & Therapeutic Uses

    • Flucytosine is used for treating candidiasis and cryptococcosis
    • For severe infections, flucytosine should be combined with amphotericin B

    Side Effects and Adverse Reactions

    • Bone marrow suppression is the most serious side effect leading to neutropenia or thrombocytopenia, and, rarely, agranulocytosis
    • Hepatotoxicity is common with flucytosine, presenting as mild and reversible hepatic dysfunction, but severe hepatic injury is rare.

    Precautions and Contraindications

    • Use with caution in patients with renal impairment because of the prolonged half-life
    • Dosage must be reduced in patients with renal insufficiency
    • Use with caution in patients with hematologic disorders and bone marrow suppression

    Drug Interactions

    • Amphotericin B can cause nephrotoxicity and may increase flucytosine toxicity.
    • Flucytosine can inhibit CYP450 enzymes, increasing the risk of fatal dysrhythmias when used with cisapride, pimozide, dofetilide, or quinidine

    Dosing, Administration, & Client Teaching

    • Dosage varies depending on the condition, severity, and patient response
    • Flucytosine is available in 250 mg and 500 mg capsules for oral administration
    • The typical dose for patients with normal renal function is 50 - 150 mg/kg/day administered in four divided doses at 6-hour intervals
    • Dosage must be reduced for patients with renal insufficiency

    Labs to Monitor

    • Basic metabolic panel (BMP) to monitor renal function
    • Complete blood count (CBC) to monitor platelet and leukocyte counts weekly
    • Liver function tests (LFTs) to monitor for hepatotoxicity
    • Serum drug levels in patients concomitantly using amphotericin B

    Flucytosine Overview

    • Flucytosine is a pyrimidine analog antifungal agent with narrow-spectrum activity.
    • Its primary function is to inhibit fungal DNA and RNA synthesis.
    • Flucytosine is primarily effective against susceptible strains of Candida and Cryptococcus neoformans.
    • Due to developing resistance, flucytosine is usually used in combination with amphotericin B.

    Mechanism of Action

    • Flucytosine is taken up by fungal cells and converted into 5-fluorouracil (5-FU), a potent antimetabolite.
    • 5-FU disrupts fungal DNA and RNA synthesis.
    • Mammals lack cytosine deaminase, the enzyme responsible for converting flucytosine to 5-FU, making the drug relatively harmless to humans.

    Indications and Therapeutic Uses

    • Flucytosine is indicated for treating candidiasis and cryptococcosis.
    • In treating severe systemic infections like candidiasis and cryptococcal meningitis, flucytosine should be combined with amphotericin B.

    Side Effects and Adverse Reactions

    • Hematologic Effects: The most severe complication is bone marrow suppression, which can lead to reversible neutropenia or thrombocytopenia, and in rare cases, fatal agranulocytosis.
    • Hepatotoxicity: Mild and reversible hepatic dysfunction commonly occurs with flucytosine use. Severe hepatic injury is rare.

    Precautions and Contraindications

    • Use caution in clients with renal impairment because of the drug's prolonged half-life. Dosage reduction is necessary for clients with renal insufficiency.
    • Exercise caution in patients with hematologic disorders or bone marrow suppression.

    Black Box Warning

    • Flucytosine has a black box warning for extreme caution in clients with renal impairment due to the long half-life.

    Drug Interactions

    • When combined with Amphotericin B, which causes nephrotoxicity, adequate kidney function is crucial to prevent flucytosine toxicity.
    • As flucytosine can inhibit CYP450 enzymes, concurrent use with cisapride, pimozide, dofetilide, or quinidine can increase their plasma levels, raising the risk of fatal dysrhythmias.

    Dosing, Administration, & Client Teaching

    • Dosing varies based on the condition, severity, and patient response. Consult drug dosing guidelines for individualized dosing.
    • Flucytosine is often administered in combination with amphotericin B.
    • Oral administration is the preferred method for the drug.
    • Dosing for clients with normal renal function is 50–150 mg/kg/day, administered in four divided doses at 6-hour intervals.
    • Dosage must be reduced for clients with renal insufficiency.

    Labs to Monitor

    • Monitor renal function using a Basic Metabolic Panel (BMP), including BUN/Creatine and Creatinine Clearance.
    • Monitor platelet and leukocyte counts weekly using a Complete Blood Count (CBC).
    • Monitor liver function tests (LFTs) weekly to assess for hepatotoxicity.
    • Monitor flucytosine levels in clients using amphotericin B concurrently.

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