Temozolomide (Specialist drug)

How it works

It is converted to the active compound MTIC, which methylates DNA, leading to DNA damage and tumour cell death.

Prescribing in practice

• It causes dose-related myelosuppression, particularly thrombocytopenia and neutropenia, so blood counts must be checked before and during treatment and dosing withheld or adjusted accordingly.
• Pneumocystis pneumonia prophylaxis is required during prolonged concomitant radiotherapy regimens.
• It is teratogenic; effective contraception is required during and after treatment, and it should be taken on an empty stomach to reduce variability in absorption and nausea.

Monitoring

Monitor full blood count before each cycle and at defined intervals, together with liver function during treatment.

Counselling the patient

• Swallow the capsules whole without opening them and avoid skin or mucosal contact with the contents.
• Take an antiemetic as prescribed and report fever, bruising, bleeding or persistent sore throat promptly.
• Use reliable contraception and discuss fertility before starting treatment.

Evidence & guidelines

Combined temozolomide and radiotherapy improved survival in glioblastoma in the landmark Stupp regimen trial.