- Class: Antimetabolite – pyrimidine analog (cytosine analog).
- Type: IV, subcutaneous, intrathecal cytotoxic chemotherapy.
Mechanism of Action (MOA)
- Analog of cytidine → converted intracellularly to cytarabine triphosphate (ara-CTP).
- Incorporates into DNA → inhibits DNA polymerase → prevents DNA synthesis → S-phase specific cytotoxicity.
- Can also interfere with RNA synthesis at high doses.
Clinical Uses
- Acute myeloid leukemia (AML) – induction and consolidation therapy.
- Acute lymphoblastic leukemia (ALL) – intrathecal prophylaxis or treatment of CNS disease.
- Other hematologic malignancies – e.g., high-grade lymphomas, chronic myelogenous leukemia (blast phase).
Dosing (Adults)
- Standard-dose IV: 100–200 mg/m²/day as continuous infusion for 7 days (AML induction).
- High-dose IV: 2–3 g/m² IV every 12 hours for 3–6 days (AML consolidation).
- Intrathecal: 12–30 mg per dose depending on age and regimen.
- Dose adjustments for renal impairment and CNS toxicity risk.
Toxicities
- Hematologic: profound neutropenia, thrombocytopenia, anemia – dose-limiting.
- Neurotoxicity: cerebellar syndrome (ataxia, dysarthria) – more common with high-dose IV.
- Gastrointestinal: nausea, vomiting, mucositis.
- Conjunctivitis – may require steroid eye drops with high-dose regimens.
- Hepatotoxicity – transient LFT elevation.
- Rare: pulmonary toxicity, rash.
Monitoring
- CBC with differential – daily during high-dose therapy.
- Neurologic assessment – especially in high-dose IV regimens.
- Liver function tests.
- Renal function.
- Eye care for high-dose therapy (lubricating or steroid eye drops).
Summary
Cytarabine (Cytosar-U®) is an S-phase specific antimetabolite used in AML and ALL, including intrathecal CNS prophylaxis. Key concerns are myelosuppression, neurotoxicity (cerebellar), mucositis, and conjunctivitis, requiring frequent CBC, neurologic monitoring, and eye care with high-dose therapy.