How should temozolomide be taken during radiotherapy?

During radiotherapy, the timing of temozolomide administration is critical to ensuring treatment effectiveness and patient safety. The dose of temozolomide is usually calculated based on the patient's body surface area, with a daily dose of 75 mg/m ². This dose needs to be taken continuously during radiotherapy to ensure that the drug and radiotherapy work synergistically. Temozolomide should be taken orally on an empty stomach, that is, avoid eating for at least 2 hours before and after taking the drug to ensure that drug absorption is not affected by food.

Most doctors recommend that patients take temozolomide at the same time every day, such as taking it in the morning before breakfast, or at least 2 hours before going to bed and after dinner. This helps maintain stable blood drug concentrations and improves therapeutic efficacy. Some doctors also recommend taking temozolomide orally 1 hour before radiotherapy. In theory, this can produce the greatest synergy with radiotherapy and further enhance the killing effect on tumor cells. However, this arrangement requires patients to strictly adhere to the radiotherapy schedule to avoid time conflicts affecting medication intake.

During radiation therapy, complete blood counts need to be monitored weekly because temozolomide may cause a decrease in platelet and neutrophil counts. Once platelets are found to be below 1010,000/μL or the absolute neutrophil count is less than 1500/μL, temozolomide treatment should be suspended until the blood cell count returns to normal.

Temozolomide may cause gastrointestinal reactions such as nausea and vomiting, so it is recommended to pre-administer antiemetics, such as ondansetron8 mg orally, 30 minutes before each dose to reduce these adverse reactions. Both temozolomide and ondansetron may cause constipation. Doctors should instruct patients to maintain good bowel habits and use laxative drugs if necessary.