Cytarabine (Cytosine Arabinoside, Ara-C)

Cytarabine (Cytosine arabinoside, Ara-C): Uses, Dosage and Side Effects

Overview

• DNA is incorporated by ara-CTP, which blocks pyrimidine and DNA synthesis.
• Cytarabine is an S-phase-specific.

Uses of Cytarabine 

• Lymphoproliferative and myeloproliferative disease management.
• Cytarabine in a VCAA combination protocol may enhance survival for dogs with bone marrow-involved lymphoma.
• Cytarabine is widely used to treat dog meningoencephalitis of uncertain origin (MUO, previously GME) and other suspected immune-mediated encephalitides.
• Prednisolone-cytarabine combination therapy is widely recorded, but the best treatment protocol is unknown.

Dose of Cytarabine in Dogs and Cats

Dogs, Cats:

Lymphoproliferative neoplastic disease: 100–150 mg/m2 given i.v. or s.c. over 2–5 days (as part of a VCAA-based protocol), or 100 mg/m2 by continuous i.v. infusion over 24–96h, or 20 mg/m2 intrathecally q1–5d. Or 200 mg/m2 given i.v. (over 4 hours) or s.c. once every two weeks as part of the DMAC protocol.

MUO/GME: 50 mg/m2 s.c. q12h for 4 doses. Repeat at 3, 7, 11, 16, 21, 27 and 33 weeks (if clinical benefit seen), then stop. CRI (100 mg/m2 CRI over 24h) at the same intervals.

Side Effects of Cytarabine in Dogs and Cats

• Vomiting, diarrhea, leucopenia.
• As it is a myelosuppression, careful hematological monitoring is required.
• Conjunctivitis, oral ulceration, neurotoxicity, hepatotoxicity, and fever
  have also been seen.
• Calcinosis cutis has been reported at the site of injection in three dogs.

Contraindications of Cytarabine in Dogs and Cats

Do not use if there is evidence of substantial hepatic impairment or bone marrow suppression.

Some Notes:

• Cytarabine decreases Digoxin oral uptake.
• Gentamicin’s activity could be hindered.
• Cytarabine’s effect is enhanced when methotrexate is administered concurrently.