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temozolomide (Temodar, Methazolastone)

Indications: - refractory anaplastic astrocytoma (FDA approved use) - metastatic malignant melanoma - glioblastoma multiforme at 1st relapse - used in connection with radiation therapy for glioblastoma [6] - Ewing sarcoma [4] - islet cell tumor [4] Dosage: 1) start: 150-200 PO mg/m2/day for 5 days of 30 day cycle 2) postpone next dose until: a) absolute neutrophil count > 1500/m3 b) platelet count > 100,000/mm3 3) if absolute neutrophil count drops < 1000/mm3, or platelet count drops < 50,000/mm3, reduce next dose by 50 mg/m2/day 4) capsules should be taken on an empty stomach, preferably at bedtime 5) do NOT open, crush or chew capsules Capsules: 5 mg, 20 mg, 100 mg, 250 mg. prophylaxis for pneumocystis pneumonia indicated with prolonged daily therapy [5] Pharmacokinetics: -> good penetration of blood brain barrier [3] Adverse effects: 1) myelosuppression a) neutropenia & thrombocytopenia b) nadir at 22-28 days 2) nausea/vomiting (50%) 3) headache (41%) 4) constipation (33%) 5) convulsions (23%) 6) hemiparesis (18%) 7) diarrhea (16%) 8) fever (13%) 9) asthenia (13%) 10) dizziness (12%) 11) amnesia (10%) 12) insomnia (10%) Mechanism of action: 1) oral imidazotetrazine derivative 2) parent compound is not cytotoxic 3) rapidly hydrolyzed to active metabolite monomethyl triazenoimidazole carboxamide (MTIC) 4) MTIC is an alkylating agent, alkylating O6 & N7 positions of guanine

Interactions

drug adverse effects of alkylating agents

General

alkylating agent triazene

Database Correlations

PUBCHEM cid=5394

References

  1. Kaiser Permanente Pharmacy update
  2. Kaiser Permanente Northern California Regional Drug Formulary, 2000
  3. Levin et al, Neoplasms of the central nervous system, in: Cancer: Principles & Practice of Oncology, DeVita et al, eds, Lippincott, Williams & Wilkins, Philadelphia, 2001, pg 2119
  4. Deprecated Reference
  5. Medical Knowledge Self Assessment Program (MKSAP) 17, American College of Physicians, Philadelphia 2015
  6. Perry JR, Laperriere N, O'Callaghan CJ Short-Course Radiation plus Temozolomide in Elderly Patients with Glioblastoma. N Engl J Med 2017; 376:1027-1037. March 16, 2017 PMID: 28296618 http://www.nejm.org/doi/full/10.1056/NEJMoa1611977