Home Drug Guide Temozolomide

Drug Guide

Generic Name

Temozolomide

Brand Names Temodar

Classification

Therapeutic: Antineoplastic, Alkylating Agent

Pharmacological: Alkylating Agent, Imidazotetrazine

FDA Approved Indications

  • Treatment of adult patients with newly diagnosed glioblastoma multiforme (in combination with radiotherapy)
  • Treatment of glioblastoma multiforme (recurrence)
  • Treatment of adult patients with refractory anaplastic astrocytoma

Mechanism of Action

Temozolomide is an oral alkylating agent that methylates DNA at the O6 and N7 positions of guanine residues, leading to DNA damage, apoptosis, and cell death, particularly in tumor cells.

Dosage and Administration

Adult: Typically 150-200 mg/m² once daily for 5 days in 28-day cycles, concomitantly with radiotherapy or as monotherapy for recurrent disease, adjusted based on patient tolerance.

Pediatric: Not recommended for pediatric use due to limited data.

Geriatric: No specific dosage adjustment, but caution due to potential increased risk of adverse effects.

Renal Impairment: Use with caution; no specific dose adjustment recommended but monitor closely.

Hepatic Impairment: Use with caution; no specific dose adjustment recommended.

Pharmacokinetics

Absorption: Rapidly absorbed following oral administration.

Distribution: Widely distributed, crosses blood-brain barrier.

Metabolism: Spontaneously hydrolyzed at physiological pH to active metabolite MTIC and then to Breakdown products.

Excretion: Primarily via urine.

Half Life: Approximately 1.8 hours for the parent drug.

Contraindications

  • Hypersensitivity to temozolomide or any component.
  • Bone marrow suppression with active infection.

Precautions

  • Myelosuppression; closely monitor blood counts.
  • Infection risk; monitor for signs of infection.
  • Pregnancy and lactation; avoid use as teratogenic.

Adverse Reactions - Common

  • Myelosuppression (neutropenia, thrombocytopenia, anemia) (Common)
  • Nausea and vomiting (Common)
  • Fatigue (Common)
  • Hair loss (Less common)

Adverse Reactions - Serious

  • Severe myelosuppression leading to infection or bleeding (Serious)
  • Secondary malignancies (rare) (Rare)
  • Liver dysfunction (Rare)

Drug-Drug Interactions

  • Cytochrome P450 inducers or inhibitors may affect metabolism.
  • Agents causing myelosuppression (e.g., radiation, other chemotherapeutics).

Drug-Food Interactions

  • No significant interactions noted.

Drug-Herb Interactions

  • Limited data; caution with herbal supplements that affect blood counts or liver enzymes.

Nursing Implications

Assessment: Monitor complete blood counts regularly, especially during treatment cycles.

Diagnoses:

  • Risk for infection due to myelosuppression.
  • Imbalanced nutrition: less than body requirements due to nausea.

Implementation: Administer as prescribed, monitor blood counts, assess for side effects.

Evaluation: Evaluate blood counts regularly; assess for signs of infection, bleeding, or adverse reactions.

Patient/Family Teaching

  • Report signs of infection, unusual bleeding, or fatigue.
  • Use effective contraception during and for at least 6 months after therapy.
  • Avoid pregnancy and breastfeeding during treatment.
  • Report severe nausea or vomiting; take antiemetics as prescribed.

Special Considerations

Black Box Warnings:

  • Myelosuppression may be severe and life-threatening. Regular CBC monitoring is essential.
  • Secondary malignancies have been reported.

Genetic Factors: Patients with certain genetic polymorphisms in DNA repair genes may have different responses or risks.

Lab Test Interference: May cause thrombocytopenia and leukopenia, affecting lab tests.

Overdose Management

Signs/Symptoms: Severe myelosuppression, infection, bleeding.

Treatment: Supportive care — hematopoietic growth factors, transfusions, infection management; no specific antidote.

Storage and Handling

Storage: Store at room temperature (20-25°C), protected from light.

Stability: Stable under recommended storage conditions.

🛡️ 5 Critical Medication Safety Tips for Nurses

1

Triple-Check High-Risk Medications

Always have another nurse verify insulin, heparin, warfarin, and chemotherapy drugs. These "high-alert" medications cause the most serious errors. Check concentration, dose calculation, and pump settings twice.

2

Know Look-Alike, Sound-Alike Drugs

Common mix-ups: hydromorphone/morphine, Celebrex/Celexa, Zyprexa/Zyrtec. Always use BOTH generic and brand names, read labels twice, and use barcode scanning when available. One wrong letter can be fatal.

3

Assess Before AND After Giving Meds

Check vitals before cardiac meds, pain levels before analgesics, and blood glucose before insulin. Always reassess within 30 minutes to evaluate effectiveness and watch for adverse reactions.

4

Watch for Drug Interactions

Common dangerous combinations: warfarin + aspirin (bleeding), ACE inhibitors + potassium (hyperkalemia), digoxin + diuretics (toxicity). Always check drug interactions before administering new medications.

5

Educate Your Patients

Teach patients medication names, purposes, major side effects, and what to report. Informed patients catch errors and improve compliance. Always encourage questions - an educated patient is a safer patient.

⚡ Remember: When in doubt, don't give it out! It's always safer to double-check than regret later.

⚠️ Medical Disclaimer

This drug guide is for educational purposes only and is NOT intended for clinical use. Always consult current prescribing information, healthcare providers, and institutional protocols before administering any medication. Do not use this information for patient care decisions.