Temozolomide
Temozolomide is an oral alkylating antineoplastic agent used in veterinary oncology. Preliminary investigations have evaluated its use primarily in canine **lymphoma**, **melanoma**, and **gliomas**. > **WARNING**: Temozolomide is a potent **cytotoxic drug**. It should only be prepared and administered by trained personnel following strict chemotherapeutic safety and handling guidelines.
Mechanism: Temozolomide acts as an **oral alkylating agent**. It undergoes rapid chemical conversion at physiologic pH to the active compound, MTIC. **Mechanism of Action**: Alkylates/methylates DNA (most often at the **N-7 or O-6 positions of guanine residues**) → DNA methylation → DNA damage → **Cell death** (apoptosis).
Dosing by species
- Lymphoma, melanoma, and gliomas · 60-65 mg/m2 · PO · q24h · for 5 consecutive days on a monthly basis (28 days) for 4 to 6 cycles
- Relapsed lymphoma · 100 mg/m2 · PO · q24h · for 5 consecutive days every 2 weeks
- Not advised · Not advised · PO · Not advised based on early toxicity studies.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Routes of administration
Contraindications
- Known hypersensitivity to temozolomide
- Pre-existing bone marrow suppression
Adverse effects
- Myelosuppression (bone marrow suppression)
- Gastrointestinal toxicity (vomiting, diarrhea, anorexia)
- Lethargy
- Polydipsia
- Altered renal parameters
- Altered hepatic parameters
Monitoring
- Complete Blood Count (CBC) prior to each cycle and at nadir
- Renal function panel
- Hepatic function panel
- Clinical signs of GI toxicity or lethargy
Overdose
**Overdose** may lead to severe and potentially fatal **myelosuppression** (pancytopenia) and severe **gastrointestinal toxicity**. * **Treatment**: There is no specific antidote. Treatment is strictly supportive, including broad-spectrum antibiotics for neutropenia, blood transfusions if necessary, and aggressive antiemetic/fluid therapy.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.