28/11/2025
CYTARABINE (Ara-C)
Cytarabine is a pyrimidine analogue antimetabolite widely used in the treatment of acute leukemias, especially Acute Myeloid Leukemia (AML). Inside the cell, it is converted to Ara-CTP, which incorporates into DNA and inhibits DNA polymerase, leading to chain termination and apoptosis. It is most active in the S-phase of the cell cycle.
🔹 Class
Antimetabolite – Pyrimidine analogue
🔹 Subclass
Pyrimidine antagonist
🔹 Mechanism of Action (MOA)
Converts to Ara-CTP, the active metabolite
Inhibits DNA polymerase
Incorporates into DNA → chain termination
Blocks DNA replication
Induces programmed cell death
Cell cycle–specific (S-phase)
🔹 Indications
AML induction (7+3 regimen)
Acute Lymphoblastic Leukemia (ALL)
CML blast crisis
CNS prophylaxis/therapy (intrathecal cytarabine)
🔹 Dosage
Adults:
Standard dose: 100–200 mg/m²/day IV × 7 days
High-dose Cytarabine (HiDAC): 1–3 g/m² IV q12h × 6 doses
Pediatrics:
Dose varies with protocols (ALL/AML-specific)
Intrathecal: 20–50 mg, age-based
🔹 Side Effects
Myelosuppression (dose-limiting)
Cerebellar toxicity → ataxia, slurred speech, nystagmus
Chemical conjunctivitis (requires steroid eye drops during HiDAC)
Hepatotoxicity
Tumor lysis syndrome (TLS)
GI toxicity, mucositis
Rash, fever
🔹 Contraindications
Severe bone marrow suppression
Hypersensitivity to the drug
Use with caution in:
Renal impairment
Hepatic dysfunction
Pre-existing neurological disease (↑ risk of neurotoxicity)
