Temozolomide, a triazene, is an inactive prodrug. It is chemically hydrolysed to 3-methyl-(triazen-1-yl) imidazole-4-carboxamide (MTIC), the active metabolite of dacarbazine. The cytotoxicity of MTIC is believed to be due alkylation of DNA, mainly at the O⁶ and N⁷ positions of guanine.

Newly Diagnosed Glioblastoma Multiforme: Temozolomide is indicated for the treatment of adult patients with newly diagnosed glioblastoma multiforme concomitantly with radiotherapy and then as maintenance treatment.

Refractory Anaplastic Astrocytoma: Temozolomide is indicated for the treatment of adult patients with refractory anaplastic astrocytoma, i.e., patients who have experienced disease progression on a drug regimen containing nitrosourea and procarbazine.

Newly diagnosed glioblastoma multiforme: 75 mg/m² for 42 days concomitant with focal radiotherapy followed by initial maintenance dose of 150 mg/m² once daily for Days 1-5 of a 28-day cycle of Temozolomide for 6 cycles

Refractory Anaplastic Astrocytoma: Initial dose 150 mg/m² once daily for 5 consecutive days per 28-day treatment cycle. 

The recommended dose for Temozolomide as an intravenous infusion over 90 minutes is the same as the dose for the oral capsule formulation. Bioequivalence has been established only when Temozolomide for Injection was given over 90 minutes

Administration

Should be taken on an empty stomach. Take at least 1 hr before meals.

Hypersensitivity to dacarbazine. Severe myelosupression. Pregnancy.

Nausea, vomiting, taste perversion, constipation, diarrhoea, abdominal pain, stomatitis, anorexia, headache, fatigue, convulsions, dizziness, memory impairment, impaired concentration, tremors, blurred vision, hearing impairment, speech disorder, rash, infection, oral candidiasis, dyspnoea, coughing, neutropenia, thrombocytopenia, leucopenia, anaemia, hyperglycemia, decreased wt, insomnia, anxiety, alopecia, muscle weakness, urinary incontinence, increased alanine aminotransferase. Rarely, myelodysplastic syndrome and secondary malignancies.

Severe hepatic and renal impairment. Elderly >70 yr, children. Women of child bearing potential should avoid becoming pregnant during therapy. Males should be advised not to father a child up to 6 mth after treatment and to consider cryoconservation of sperms due to possibility of irreversible infertility. Unknown if distributed into breastmilk, discontinue nursing due to potential risk. May impair ability to drive or operate machinery. Swallow capsules whole with a full glass of water on an empty stomach or at bedtime. Do not take a 2nd dose if capsules are vomited. Monitor CBC wkly during concomitant therapy and on day 22 of each 28 day treatment cycle, followed by wkly blood count until recovery. Hepatitis screening and prophylactic therapy with antiviral agents as clinically indicated to be considered. Prophylaxis for Pneumocystis jiroveci (or Pneumocystis carinii) pneumonia (PCP) needed for all patients receiving concomitant temozolomide and radiation therapy for the 42-day regimen; if patients experience lymphocytopenia during the concomitant phase of therapy, PCP prophylaxis should be continued until recovery from lymphocytopenia. Monitor closely for PCP development in all patients. Anti-emetic prophylaxis recommended.

Use in Special Populations

Pediatric Use: Safety and effectiveness in pediatric patients have not been established.

Geriatric Use: Clinical studies of temozolomide did not include sufficient numbers of subjects aged 65 and over to determine whether they responded differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.

Renal Impairment: Caution should be exercised when temozolomide is administered to patients with severe renal impairment

Hepatic Impairment: Caution should be exercised when temozolomide is administered to patients with severe hepatic impairment

Pregnancy & Lactation

Pregnancy Category D. There is positive evidence of human foetal risk, but the benefits from use in pregnant women may be acceptable despite the risk (e.g., if the drug is needed in a life-threatening situation or for a serious disease for which safer drugs cannot be used or are ineffective).

Nursing Mothers: It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants and tumorigenicity shown for temozolomide in animal studies, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of Temozolomide to the mother.