[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Alkylating agents](https://durgical.com/en/pharmacology/classes/alkylating-agents/) › Temozolomide # Temozolomide ## Alkylating agents? Alkylating agents ## High alert? An error with this medicine can cause serious harm: double checks and protocols are used. An oral methylating drug that turns into MTIC by itself and reaches the brain. With radiotherapy it is the standard drug for glioblastoma. Updated Nov 1, 2026 ## Quick facts **Group** [Alkylating agents](https://durgical.com/en/pharmacology/classes/alkylating-agents/) **Target** DNA (guanine O6 and N7), methylated by MTIC **Used for** Newly diagnosed glioblastoma · Anaplastic astrocytoma **Key effects** Nausea · Fatigue · Hair loss **Monitor** Liver tests at baseline **ATC** L01AX03 No doses: the clinician sets them by the current guideline. On this page - The basics Mechanism of action - Indications - Adverse effects - Pharmacokinetics - Memory aid - Clinical What the labels mean - Safety Contraindications - Key interactions - What is monitored - Administration and safety - Pregnancy and breastfeeding - Nursing care - Study Test yourself - Connections Connections ## Mechanism of action Temozolomide needs no enzyme: at the body's normal pH it opens up into MTIC, the same active compound made from dacarbazine. MTIC releases a methyl group that attaches to guanine, mainly at O6 and N7. O6-methylguanine is mispaired during copying; repeated failed repair causes DNA breaks and cell death. The repair enzyme MGMT removes the methyl group, so tumours that have silenced the MGMT gene respond better. - At body pH temozolomide opens into MTIC - MTIC methylates guanine (O6 and N7) - Mispaired O6-methylguanine leads to DNA breaks - Tumours lacking MGMT repair respond best ## Indications - Newly diagnosed glioblastoma, with radiotherapy and then as maintenance. [Glioblastoma →](https://durgical.com/en/conditions/glioblastoma/) - Anaplastic astrocytoma (adjuvant or refractory). ## Adverse effects ### Common - Nausea, vomiting, constipation - Fatigue, headache - Hair loss - Low lymphocytes, neutrophils and platelets ### Serious (rare, important) - Myelosuppression, more frequent in older patients and in women - Pneumocystis pneumonia linked to lymphopenia, especially with corticosteroids - Severe and fatal liver injury - Myelodysplasia and secondary leukaemia ## Contraindications - Serious hypersensitivity to temozolomide or its ingredients - Serious hypersensitivity to dacarbazine (same active metabolite) ## Key interactions **Corticosteroids (e.g. dexamethasone for brain oedema)** Deepen lymphopenia and raise the risk of Pneumocystis pneumonia. **Other myelosuppressive drugs and radiotherapy** Add to bone marrow suppression. ## What is monitored - Neutrophil and platelet counts before each cycle and during treatment - Liver tests at baseline, during the first cycle, before each cycle and after the last dose - Lymphocyte count and signs of pneumonia ## Administration and safety - Capsules are swallowed whole and never opened or chewed; contents on skin or mucosa are washed off at once. - Taken on an empty stomach or at bedtime to reduce nausea, with an antiemetic as prescribed. - Pneumocystis prophylaxis is used during the combined radiotherapy phase. ## Pregnancy and breastfeeding Can cause fetal harm; women use effective contraception and men use condoms with partners who could become pregnant. ## Nursing care - Check counts and liver tests before each cycle. - Confirm the patient understands the exact cycle schedule: mistakes with oral chemotherapy cause overdoses. - Watch for cough, fever and breathlessness (Pneumocystis), especially on corticosteroids. - Teaching: safe handling and storage at home; contraception (men use condoms). ## Pharmacokinetics **Absorption** Oral, well absorbed; it is taken the same way each time with respect to food. **Distribution** Small and lipid-soluble: it crosses the blood–brain barrier. **Metabolism** Spontaneous chemical conversion to MTIC; little liver metabolism. **Elimination** Mainly in the urine. ## Memory aid «TMZ: Turns into MTIC with Zero enzymes»; works best when MGMT is silent, and watch for PCP with steroids. ## Test yourself Think of the answer, then tap the question to see it. ## How is temozolomide activated? Spontaneously at physiological pH, to MTIC; no liver enzyme is needed. ## Which tumour feature predicts a better response to temozolomide? Silencing (methylation) of the MGMT gene, which removes the repair of O6-methylguanine. ## Why is temozolomide contraindicated after a serious reaction to dacarbazine? Both are converted to the same active metabolite, MTIC. ## Which opportunistic infection is a concern with temozolomide and corticosteroids? Pneumocystis jirovecii pneumonia. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/pharmacology/temozolomide/) [More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology) ## What the labels mean **High alert** An error with this medicine can cause serious harm: double checks and protocols are used. ## Connections ## Related drugs 3 - [Dacarbazine](https://durgical.com/en/pharmacology/dacarbazine/) - [Carmustine](https://durgical.com/en/pharmacology/carmustine/) - [Lomustine](https://durgical.com/en/pharmacology/lomustine/) ## Related conditions 1 - [Glioblastoma](https://durgical.com/en/conditions/glioblastoma/) [← Back to the class: Alkylating agents](https://durgical.com/en/pharmacology/classes/alkylating-agents/) Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given. Sources: [DailyMed - TEMOZOLOMIDE capsule](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=9dff10ec-6a55-47b6-a458-b7c39e32dc55) (DailyMed (U.S. National Library of Medicine), 2026); [Temozolomide: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a601250.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=L01AX03) (WHO Collaborating Centre for Drug Statistics Methodology, 2026). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/pharmacology/temozolomide/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/temozolomide/