💊 GBM Medications Guide

Understanding the medications commonly prescribed for glioblastoma treatment, their side effects, and important interactions.

💉 Chemotherapy

Temozolomide (TMZ)
Brand name: Temodar
Chemotherapy

The standard chemotherapy for GBM. An oral medication (capsules) that crosses the blood-brain barrier.

How It's Given

  • During radiation: Daily, 7 days/week (lower dose: 75 mg/m²)
  • After radiation: Days 1-5 of each 28-day cycle (higher dose: 150-200 mg/m²)
  • Usually continued for 6-12 cycles after radiation

Common Side Effects

  • Nausea and vomiting (take anti-nausea meds before)
  • Fatigue
  • Low blood counts (neutropenia, thrombocytopenia)
  • Constipation
  • Headache
💡 Tips for Taking TMZ:
  • Take on an empty stomach or at bedtime to reduce nausea
  • Take anti-nausea medication 30-60 minutes before
  • Do NOT open capsules
  • Stay well hydrated
⚠️ Important: You'll need regular blood tests (CBC) to monitor blood counts. Low counts may require dose adjustments or treatment delays.
Bevacizumab
Brand name: Avastin
Targeted Therapy

An anti-angiogenic drug that blocks blood vessel growth to tumors. Often used at recurrence, sometimes with initial treatment.

How It's Given

  • IV infusion every 2-3 weeks
  • First infusion takes 90 minutes; subsequent can be shorter if tolerated

Side Effects to Watch

  • High blood pressure (monitor regularly)
  • Increased bleeding/bruising risk
  • Delayed wound healing
  • Protein in urine
  • Fatigue
🚨 Serious Risks: Blood clots, GI perforation (rare), severe bleeding. Report severe abdominal pain, chest pain, or unusual bleeding immediately.

💪 Steroids (Dexamethasone)

Dexamethasone
Brand names: Decadron, various generics
Corticosteroid

Reduces brain swelling (edema) around the tumor. Critical for managing symptoms but has significant side effects with long-term use.

Why It's Used

  • Reduces swelling around the tumor
  • Decreases pressure in the skull
  • Improves neurological symptoms (weakness, speech, etc.)
  • Often needed during and after radiation

Common Side Effects

  • Short-term: Increased appetite, insomnia, mood changes, high blood sugar
  • Long-term: Weight gain, muscle weakness (especially legs), osteoporosis, skin thinning, increased infection risk, cushingoid appearance (moon face)

Managing Dexamethasone Side Effects

  • Insomnia: Take all doses before 2 PM if possible
  • Blood sugar: Monitor if diabetic or pre-diabetic; limit sweets
  • Appetite: Have healthy snacks available; don't keep junk food in the house
  • Mood swings: Warn family members; consider counseling support
  • Muscle weakness: Light exercise when able; physical therapy
  • Stomach protection: Often given with a PPI (like omeprazole) to prevent ulcers
🚨 Never Stop Suddenly: Dexamethasone must be tapered slowly. Stopping suddenly can cause adrenal crisis, which is life-threatening. Always follow your doctor's tapering schedule.

Example Tapering Schedule

This is an example only - your doctor will create your specific plan:

Week 1
4mg twice daily
Week 2
4mg + 2mg
Week 3
2mg twice daily
Week 4
2mg once daily
Week 5
1mg once daily
Week 6
0.5mg → stop
💡 Goal: Use the lowest effective dose for the shortest time. Ask your doctor regularly if you can try reducing. Some patients can wean off completely; others need a maintenance dose.

⚡ Anti-Seizure Medications

About 30-50% of GBM patients experience seizures. Anti-epileptic drugs (AEDs) are often prescribed preventively or after a seizure occurs.

Levetiracetam
Brand name: Keppra
Anti-Seizure

First-line choice for GBM patients because it has fewer drug interactions.

Side Effects

  • Mood changes, irritability ("Keppra rage")
  • Fatigue
  • Dizziness
  • Weakness
💡 Tip: Vitamin B6 (pyridoxine) may help reduce irritability from Keppra. Ask your doctor about supplementation.
Lacosamide
Brand name: Vimpat
Anti-Seizure

Alternative when Keppra isn't tolerated. Also has minimal drug interactions.

Side Effects

  • Dizziness
  • Headache
  • Nausea
  • Double vision
Valproic Acid
Brand name: Depakote
Anti-Seizure

Older medication, still sometimes used. Some research suggests it may enhance TMZ effectiveness.

Side Effects

  • Weight gain
  • Tremor
  • Hair loss
  • Liver enzyme changes (requires monitoring)
⚠️ Drug Interactions: Valproic acid has more drug interactions than Keppra. Can increase bleeding risk with blood thinners.
⚠️ Phenytoin (Dilantin) & Carbamazepine (Tegretol): These older anti-seizure medications can reduce the effectiveness of chemotherapy by speeding up how the body metabolizes drugs. They are generally avoided in GBM patients.

🛡️ Supportive Medications

Ondansetron
Brand name: Zofran
Anti-Nausea

Take 30-60 minutes before chemotherapy to prevent nausea.

Omeprazole / Pantoprazole
PPIs (Proton Pump Inhibitors)
Stomach Protection

Protects stomach lining when taking steroids. Usually taken in the morning.

Trimethoprim-Sulfamethoxazole
Brand name: Bactrim
Infection Prevention

Prevents PCP pneumonia during radiation + temozolomide (when immune system is suppressed). Usually taken 3x per week.

⚠️ Important Drug Interactions

Substance Interaction With Effect
Grapefruit juice Many medications Can increase or decrease drug levels unpredictably
St. John's Wort Chemotherapy, seizure meds Reduces effectiveness - AVOID
High-dose Vitamin E Blood thinners, surgery Increases bleeding risk
NSAIDs (ibuprofen) Steroids, blood thinners Increases stomach bleeding and ulcer risk
Alcohol Seizure meds, TMZ, steroids Increases side effects, liver stress
💡 Always Tell Your Care Team: About ALL supplements, vitamins, and over-the-counter medications you take. Even "natural" products can have significant interactions.

📋 Medication Management Tips

  • Use a pill organizer: Weekly organizers help track what's been taken
  • Set alarms: Especially for medications with specific timing requirements
  • Keep a medication list: Include doses, times, and prescribing doctor
  • Use one pharmacy: They can check for interactions across all prescriptions
  • Don't skip doses: But if you miss one, don't double up without asking
  • Store properly: Keep TMZ capsules at room temperature, away from moisture
  • Plan ahead: Get refills before you run out; some meds require special ordering

⚠️ Medical Disclaimer

This guide is for educational purposes only. Medication doses, schedules, and combinations must be determined by your healthcare team based on your specific situation. Never start, stop, or change medications without consulting your doctor. If you experience severe side effects, contact your care team immediately.