Nurses Compass
Drug Guide
Flucytosine
Classification
Therapeutic: Antifungal agent
Pharmacological: Antimetabolite
FDA Approved Indications
- Cryptococcal meningitis in conjunction with Amphotericin B
- Maintenance therapy for cryptococcal meningitis after initial treatment
Mechanism of Action
Flucytosine is converted by fungal cells into 5-fluorouracil, which inhibits DNA and RNA synthesis, leading to fungal cell death.
Dosage and Administration
Adult: 25 mg/kg every 6 hours, adjusted based on renal function; typically used with Amphotericin B for cryptococcal meningitis.
Pediatric: Same as adult dosing, based on weight; dosage must be carefully adjusted for renal impairment.
Geriatric: Use with caution; renal function should be assessed.
Renal Impairment: Dose adjustment recommended based on renal function, as drug accumulation can occur.
Hepatic Impairment: No specific adjustment recommended, but monitoring advised.
Pharmacokinetics
Absorption: Well absorbed orally.
Distribution: Widely distributed in body tissues, including cerebrospinal fluid.
Metabolism: Minimal hepatic metabolism.
Excretion: Primarily excreted unchanged in urine.
Half Life: approximately 3-6 hours in patients with normal renal function.
Contraindications
- Hypersensitivity to Flucytosine.
Precautions
- Use with caution in patients with renal impairment, history of bone marrow suppression, or hepatic dysfunction.
Adverse Reactions - Common
- Gastrointestinal disturbances (nausea, vomiting, diarrhea) (Common)
- Bone marrow suppression (leukopenia, thrombocytopenia, anemia) (Common)
Adverse Reactions - Serious
- Hepatotoxicity (Rare)
- Orofacial or systemic hypersensitivity reactions (Rare)
- Agranulocytosis (Rare)
Drug-Drug Interactions
- Amphotericin B (enhanced myelosuppression)
- Radiation therapy (increased bone marrow suppression)
Drug-Food Interactions
N/ADrug-Herb Interactions
N/ANursing Implications
Assessment: Monitor renal function (BUN, serum creatinine), liver function tests, and complete blood counts regularly.
Diagnoses:
- Risk for infection due to bone marrow suppression
- Risk for injury related to hematologic abnormalities
Implementation: Administer with food to reduce gastrointestinal upset. Monitor for signs of toxicity and infection.
Evaluation: Evaluate blood counts, renal and hepatic function periodically to guide dosing and detect toxicities early.
Patient/Family Teaching
- Report symptoms of rash, fever, sore throat, bleeding, or easy bruising immediately.
- Adhere to scheduled lab tests for blood counts and liver/kidney function.
- Use medication as prescribed—do not skip doses.
- Maintain adequate hydration to assist renal excretion.
Special Considerations
Black Box Warnings:
- Myelosuppression and hepatic toxicity are serious risks, especially with prolonged therapy.
Genetic Factors: No known significant genetic factors impacting use.
Lab Test Interference: Can cause false elevation of serum creatinine.
Overdose Management
Signs/Symptoms: Gastrointestinal symptoms, hematologic toxicity, hepatic dysfunction.
Treatment: Supportive care; monitor blood counts, renal and liver function; possibly use dialysis if indicated.
Storage and Handling
Storage: Store at room temperature, protected from light.
Stability: Stable under recommended conditions for shelf life specified by manufacturer.