Temozar100 mg

Temozar is an oral alkylating chemotherapy agent used in the treatment of certain brain tumors. Its established, FDA-approved indications are:

• Newly diagnosed glioblastoma multiforme (GBM): Temozar is given together with radiotherapy (concomitant phase), followed by up to 6 cycles of Temozar alone (maintenance phase).
• Refractory anaplastic astrocytoma: Temozar is indicated in adult patients whose disease has progressed on a regimen containing a nitrosourea and procarbazine.

Temozar is also used off-label, under specialist oncology supervision, in some other central nervous system tumors (for example, recurrent or progressive low-grade gliomas, and brain metastases from melanoma) and in metastatic melanoma, based on clinical judgment and guideline support rather than formal approval. Temozar must always be prescribed and monitored by a physician experienced in cancer chemotherapy.

Each capsule of Temozolomide contains temozolomide as the active ingredient. Temozolomide capsules are commonly available internationally in strengths of 5 mg, 20 mg, 100 mg, 140 mg, 180 mg, and 250 mg; in Bangladesh, Temozolomide is marketed mainly as 100 mg and 250 mg capsules. An intravenous powder-for-infusion form of Temozolomide also exists in some markets, for use when oral therapy is not feasible. Inactive ingredients vary by manufacturer and typically include fillers such as lactose, colloidal silicon dioxide, sodium starch glycolate, tartaric acid, and stearic acid, along with the capsule shell components.

Temozar is a small-molecule, orally active alkylating agent belonging to the imidazotetrazine class of antineoplastic drugs. It is a prodrug that does not require hepatic enzymatic activation; instead it converts to its active form spontaneously at physiological pH. Temozar crosses the blood-brain barrier effectively, which underlies its usefulness in primary brain tumors such as glioblastoma. Temozar should be used only under the supervision of a physician experienced in cancer chemotherapy.

Temozar belongs to the alkylating agent class of antineoplastic (anticancer) medicines, specifically the imidazotetrazine subgroup. Temozar is a prodrug of the active alkylating species MTIC, the same reactive metabolite produced by dacarbazine.

Temozolomide undergoes rapid, spontaneous, non-enzymatic hydrolysis at physiological pH to the active compound MTIC (5-(3-methyltriazen-1-yl)imidazole-4-carboxamide), which degrades further to a reactive methyldiazonium species. Temozolomide methylates DNA primarily at the O6 and N7 positions of guanine. The resulting O6-methylguanine adducts mispair during replication, triggering a futile DNA mismatch-repair cycle that leads to DNA strand breaks, cell-cycle arrest, and apoptosis of tumor cells. Tumor cells with high levels of the DNA-repair enzyme MGMT (O6-methylguanine-DNA methyltransferase) are relatively resistant to Temozolomide. Temozolomide is well absorbed orally, distributes widely including into the central nervous system, and is eliminated with a short elimination half-life of approximately 1.8 hours, mainly through non-enzymatic degradation and renal excretion of metabolites.

Temozar capsules should be swallowed whole with a full glass of water; they must not be opened, chewed, or dissolved, as the cytotoxic powder can be hazardous if inhaled or if it contacts skin, eyes, or mucous membranes. Temozar should be taken on an empty stomach, at least one hour before a meal, at approximately the same time each day for consistent absorption. If a dose of Temozar is vomited shortly after intake, a repeat dose should not be taken the same day without specific instruction from the prescribing physician. Caregivers who are pregnant should avoid handling Temozar capsules or contact with the capsule contents.

Temozar has relatively few clinically significant drug interactions, but the following should be noted:

• Valproic acid: may modestly reduce the clearance of Temozar; the clinical significance is considered minor, but blood counts should still be monitored closely.
• Other myelosuppressive drugs or concurrent radiotherapy: combining Temozar with other bone-marrow-suppressing medicines increases the risk of severe myelosuppression.
• Live vaccines: should generally be avoided during and for some time after Temozar therapy because of treatment-related immunosuppression; consult the treating physician about vaccination timing.

Always inform the treating physician of all medicines, supplements, and vaccines used before and during Temozar therapy.

Very common side effects of Temozar include nausea, vomiting, constipation, fatigue, headache, alopecia (hair loss), and loss of appetite.

Common side effects include diarrhea, rash, fever, dizziness, memory impairment, and mild-to-moderate myelosuppression (low blood counts).

Serious side effects requiring urgent medical attention

• Severe or prolonged myelosuppression (very low white cells, platelets, or red cells), which can be unpredictable and severe with Temozar — see Precautions and Warnings.
• Signs of liver injury (yellowing of skin or eyes, dark urine, severe fatigue, abdominal pain) — hepatotoxicity associated with Temozar has been fatal in rare cases.
• Signs of infection or pneumonia, including Pneumocystis jirovecii pneumonia (PCP), especially during the phase when Temozar is combined with radiotherapy.
• Severe allergic reaction (difficulty breathing, swelling of the face or throat, severe rash).

Secondary cancers, including myelodysplastic syndrome and acute myeloid leukemia, have been reported after Temozar-based treatment, generally after prolonged use combined with other chemotherapy or radiotherapy.

Temozar can cause serious fetal harm and is classified under the older FDA system as Pregnancy Category D. Temozar should be avoided in pregnancy. If a patient becomes pregnant while taking Temozar, or if use during pregnancy is being considered, Temozar should be used only if the potential benefit, in the treating physician's judgment, justifies the potential risk to the fetus, and only after full consultation.

Effective contraception is required during Temozar treatment and for a period afterward (generally at least 6 months) for both female and male patients, since Temozar may also affect sperm and has mutagenic potential.

It is not known whether Temozar passes into breast milk. Because of the potential for serious adverse effects in a nursing infant, breastfeeding should be discontinued during treatment with Temozar. Always consult a physician before use of Temozar in pregnancy or while breastfeeding.

Temozar must be prescribed and monitored only by a physician experienced in cancer chemotherapy. Key precautions include:

• Myelosuppression: Temozar can cause severe, prolonged, and sometimes unpredictable suppression of bone marrow function. Complete blood counts must be checked before starting Temozar, on Day 22 of each cycle, and weekly if counts fall low, with dose adjustment, delay, or discontinuation as needed.
• Hepatotoxicity: Liver function tests should be performed at baseline and periodically during treatment, as severe and rarely fatal liver injury has been reported with Temozar.
• Pneumocystis jirovecii pneumonia (PCP): Patients receiving Temozar concomitantly with radiotherapy (the 42-day phase) are at increased risk of PCP due to prolonged lymphopenia and require PCP prophylaxis during this phase and until recovery of lymphocyte counts.
• Secondary malignancies: Cases of myelodysplastic syndrome and other secondary cancers, including leukemia, have been reported after Temozar therapy.
• Capsule handling: Temozar capsules must be swallowed whole and never opened or chewed; if a capsule is accidentally opened, avoid contact of the powder with skin or mucous membranes and avoid inhalation.
• Contraception: Effective contraception is required for both men and women during and after Temozar treatment (see Pregnancy and Lactation).

Overdose with Temozar can cause severe and prolonged myelosuppression and may be life-threatening; cases involving multi-organ toxicity and death have been reported with substantial overdose of Temozar. There is no specific antidote for Temozar overdose. If an overdose of Temozar is suspected, seek immediate medical attention or contact emergency services or a poison control center; the patient will require close monitoring of blood counts and organ function, with supportive care as directed by a physician.

Store Temozar at room temperature (below 30°C), away from light and moisture. Keep out of reach of children.

Renal impairment: No formal dose adjustment of Temozar is established for mild-to-moderate renal impairment; Temozar has not been specifically studied in severe renal impairment, so it should be used with caution and closer monitoring.

Hepatic impairment: Temozar requires no dose adjustment in mild-to-moderate hepatic impairment; it should be used cautiously, with close monitoring of liver function, in severe hepatic impairment.

Elderly: Patients over 70 years may have a higher risk of myelosuppression with Temozar and require close blood count monitoring.

Women: Female patients have shown a higher risk of severe myelosuppression with Temozar in clinical trials and should be monitored closely.

Children: Safety and effectiveness of Temozar have not been formally established in pediatric patients for the standard adult indications; see Pediatric Uses.

For newly diagnosed glioblastoma, the concomitant phase of Temozar lasts 42 days (up to 49 days) alongside radiotherapy, followed by a rest period and then up to 6 maintenance cycles of Temozar (28 days per cycle, taken on Days 1-5), unless disease progression or unacceptable toxicity occurs. For refractory anaplastic astrocytoma, Temozar cycles continue every 28 days as long as the patient is benefiting from and tolerating treatment. The exact duration of Temozar therapy is determined by the treating oncologist based on response and tolerability.

Alkylating agent; antineoplastic (chemotherapy) agent; imidazotetrazine derivative and prodrug of MTIC.

Temozolomide is a prodrug that spontaneously converts to the active alkylating metabolite MTIC at physiological pH, without requiring hepatic activation. MTIC methylates DNA at the O6 and N7 positions of guanine, and mismatch-repair processing of the resulting O6-methylguanine adducts leads to DNA strand breaks, cell-cycle arrest, and apoptosis of susceptible tumor cells.

D

Safety and effectiveness of Temozar have not been formally established in pediatric patients for its approved adult indications (newly diagnosed glioblastoma multiforme and refractory anaplastic astrocytoma). Temozar has been used off-label in some pediatric brain tumors (for example, high-grade glioma or brainstem glioma) in specialized pediatric oncology settings, but Temozar should only be used in children under the direct supervision of a pediatric oncologist, with close monitoring of blood counts and growth and development.