Section 14 · Monograph
Temozolomide
Reviewed Nov 2026FDA label
TemodarAlkylating agent
- Forms
- Cap: 5, 20, 100, 140, 180, 250mg | IV: 100mg vial
- Dose
- Glioblastoma: 75mg/m² daily with radiation (42-49 days), then 150-200mg/m² days 1-5 of 28-day cycles
- MOA
- DNA methylation causing tumor cell death
Indications
- Newly diagnosed glioblastoma concomitantly with radiotherapy, then as maintenanceFDA-labeled
- Refractory anaplastic astrocytomaFDA-labeled
Mechanism of Action
- Oral alkylating prodrug converted to MTIC; methylates DNA (including O6-guanine), triggering tumor cell death
- MGMT promoter methylation predicts greater benefit
Full Dosing
Adult / usual
- Concomitant phase: 75mg/m² daily for 42-49 days with radiation
- Maintenance: 150mg/m² days 1-5 of each 28-day cycle; may increase to 200mg/m² from cycle 2 if tolerated, for up to 6 cycles (longer courses are used in practice)
- PJP prophylaxis during the concomitant phase; antiemetic prophylaxis
- Swallow capsules whole with water
Contraindications
- Hypersensitivity to temozolomide or dacarbazine
Drug Interactions
- Valproic acid slightly reduces temozolomide clearance
- Additive myelosuppression with other myelosuppressive therapy
Adverse Effects
- Nausea and vomiting
- Myelosuppression (thrombocytopenia, neutropenia)
- Fatigue, headache, constipation
- Pneumocystis pneumonia
- Hepatotoxicity
- Rare secondary myelodysplasia or leukemia
Monitoring Parameters
- CBC weekly during the concomitant phase; CBC on day 22 and day 29 of cycles, requiring ANC 1500 or more and platelets 100,000 or more to proceed
- Liver tests at baseline and midcycle
- PJP prophylaxis compliance
Pregnancy & Lactation
- Embryo-fetal toxicity; use contraception during therapy and for several months after (women about 6 months, men about 3 months)
- Breastfeeding not recommended