Flucytosine

A to Z Drug Facts

 Action Exact mechanism is unknown; interferes with DNA and RNA synthesis. Active against Candida and Cryptococcus.

 Indications Treatment of serious infections caused by susceptible strains of Candida or Cryptococcus. unlabeled use(s): Treatment of Chromomycosis.

 Contraindications Standard considerations.

 Route/Dosage

ADULTS & CHILDREN > 50 kg: PO 50 to 150 mg/kg/day in divided doses q 6 hr.

 Interactions

Amphotericin B: Increased therapeutic action and toxicity of flucytosine. Cytosine: Inactivates antifungal activity of flucytosine.

 Lab Test Interferences Interferes with creatinine value determinations with dry-slide enzymatic method (Kodak Ektachem analyzer); use Jaffe method.

 Adverse Reactions

CV: Cardiac arrest. CNS: Ataxia; hearing loss; headache; sedation; confusion; fatigue; weakness; dizziness; vertigo, paresthesia; parkinsonism; peripheral neuropathy; pyrexia; hallucinations; psychosis. DERM: Rash; pruritus; urticaria; photosensitivity. GI: Nausea; emesis; abdominal pain; diarrhea; anorexia; duodenal ulcer; GI hemorrhage. GU: Azotemia; creatinine and BUN elevation; crystalluria; renal failure; dry mouth. HEMA: Anemia; agranulocytosis; aplastic anemia; eosinophilia; leukopenia; pancytopenia; thrombocytopenia. HEPA: Hepatic dysfunction; jaundice; ulcerative colitis; increased bilirubin; elevated hepatic enzymes. META: Hypoglycemia; hypokalemia. RESP: Respiratory arrest; chest pain; dyspnea.

 Precautions

Pregnancy: Category C. Lactation: Undetermined. Children: Safety and efficacy not established. Bone marrow depression: Use with extreme caution in patients with bone marrow depression or those at risk (eg, hematologic disease, radiation treatment, other bone marrow suppressant drugs). Hepatic or renal impairment: Use with extreme caution in patients with renal impairment. Adjust dose according to blood levels and monitor hepatic function.

 Administration/Storage

• Administer capsules a few at a time over 15 min to minimize GI upset.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies.
• Ensure that baseline liver function tests, BUN, and creatinine, electrolytes, and glucose have been obtained before beginning therapy, and monitor at regular intervals.
• Obtain baseline CBC with differential and repeat daily. Assess for bone marrow depression.
• Obtain specimens for culture and sensitivity before beginning therapy.
• Monitor BP at regular intervals during therapy. Assess for cardiovascular collapse.
• Monitor blood levels of drug closely in patient with impaired renal function.
• If patient has ataxia, hearing loss, headache, paresthesia, peripheral neuropathy, pyrexia, hallucinations, psychosis, laboratory evidence of liver or renal dysfunction, chest pain, or respiratory distress, notify physician immediately.

 Patient/Family Education

• Instruct patient to take capsules a few at a time over a 15-min period with food.
• Instruct diabetic patients to monitor glucose closely.
• Instruct patient to report the following symptoms to physician: Sore throat, cough, unusual bleeding or bruising, petechiae, blood in urine, bleeding gums, abdominal pain, nausea, vomiting, change in color or consistency of stools, fever, yellow skin/eyes, ataxia, hearing loss, paresthesia, shaking, tingling, altered sensation, parkinsonism, peripheral neuropathy, hallucinations or psychosis, anorexia, increased fatigue, rash or itching.
• Warn patient to seek emergency care if respiratory distress or chest pain occur.
• Advise patient that drug may cause dizziness or vertigo and to use caution while driving or performing other tasks requiring mental alertness.
• Caution patient to avoid unnecessary exposure to sunlight and to use sunscreen and wear protective clothing to avoid photosensitivity reaction.

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Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts