Capecitabine

Capecitabine Uses, Dosage, Side Effects & Brands

Capecitabine (pronounced ka-pe-site-a-been) is an oral chemotherapy drug classified as a fluoropyrimidine carbamate antimetabolite, widely used to treat several cancers including:

  • Colorectal cancer
  • Metastatic breast cancer
  • Gastrointestinal cancers
  • Pancreatic cancer
  • Gastric (stomach) cancer

✅ Indications

Capecitabine is indicated for:

First-line treatment of metastatic colorectal cancer (mCRC).

Adjuvant therapy post-surgery in Dukes’ C colon cancer.

Advanced or metastatic breast cancer resistant to anthracycline- and taxane-based therapy.

In combination with other chemotherapy or radiation for GI cancers, including pancreatic and gastric cancers.

⚙️ Mechanism of Action

Capecitabine is a prodrug, enzymatically converted into 5-fluorouracil (5-FU) in the tumor tissue. The conversion happens in three steps:

  • Capecitabine → 5′-DFCR (by carboxylesterase)
  • 5′-DFCR → 5′-DFUR (by cytidine deaminase)
  • 5′-DFUR → 5-FU (by thymidine phosphorylase, highly active in tumors)

Once converted, 5-FU disrupts tumor growth by:

  • Inhibiting thymidylate synthase, blocking DNA synthesis.
  • Incorporating into RNA, disrupting normal RNA processing.
  • Leading to apoptosis (programmed cell death).

💊 Dosage & Administration

Form: Oral tablets

Administration: Taken twice daily, within 30 minutes after meals.

Cycle: Often 14 days on treatment followed by 7 days off (21-day cycle), repeated for multiple cycles depending on cancer type.

⚠️ Always follow exact dosing instructions from your oncologist or pharmacist.

🔬 Pharmacokinetics

Parameter Details
Absorption Well absorbed orally
Tmax (Peak Level) ~1.5 hrs (Capecitabine), ~2 hrs (5-FU)
Half-life ~0.75 hrs
Volume of Distribution ~186 L
Protein Binding <60%, mostly to albumin
Metabolism Liver and tumor-specific enzymes
Elimination 96% via urine, 3% unchanged, 57% as FBAL
Clearance ~775 mL/min (in colorectal cancer patients)

⚠️ Important Tests Before Treatment

DPD deficiency screening: Tests for dihydropyrimidine dehydrogenase enzyme levels. Deficiency increases toxicity risk.

Liver and kidney function tests: To ensure safe drug metabolism and clearance.

❗ Common Side Effects (≥10%)

  1. Fatigue
  2. Loss of appetite
  3. Diarrhea
  4. Mouth sores
  5. Hand-foot syndrome (redness, peeling, pain on hands/feet)
  6. Abdominal pain
  7. Nausea or vomiting

⚠️ Occasional Side Effects (1–10%)

  • Constipation, bloating
  • Anemia, neutropenia
  • Dizziness, headache
  • Dry skin, rash, nail changes
  • Liver enzyme elevation
  • Shortness of breath

❗ Rare But Serious Side Effects (<1%)

  • Severe allergic reactions
  • Chest pain or heart attack
  • Pancreatitis
  • Pulmonary embolism
  • Severe skin reactions (e.g., Stevens-Johnson syndrome)
  • Sepsis
  • Blood clots or bleeding

🚨 When to Contact a Doctor Immediately

  • High fever (≥37.5°C) or chills

  • Uncontrolled diarrhea or vomiting

  • Mouth ulcers or bleeding gums

  • Skin peeling, blistering, or painful rash

  • Chest pain or irregular heartbeat

  • Difficulty breathing

📌 Drug Interactions & Precautions

  • Avoid grapefruit and grapefruit juice.

  • Inform your doctor of all supplements, over-the-counter medications, and herbal products.

  • Live vaccines should be avoided during treatment and for up to 12 months after.

👶 Pregnancy & Breastfeeding

  • Not safe during pregnancy — use effective contraception.

  • Avoid pregnancy for 6 months (women) or 3 months (men) post-treatment.

  • Do not breastfeed during and for 2 weeks after final treatment.

⚕️ Capecitabine Summary Table

Category Detail
Drug Class Antimetabolite, Fluoropyrimidine
Brand Name Xeloda® (among others)
Route Oral
Converted To 5-Fluorouracil (5-FU)
Used For Colorectal, breast, gastric, pancreatic cancers
Pregnancy Category Contraindicated
Monitoring CBC, liver/kidney function, DPD status
Enzyme Targets Thymidylate synthase, RNA pathways

📢 Final Thoughts

Capecitabine is a powerful, tumor-targeted chemotherapy drug with the convenience of oral administration. It offers comparable efficacy to intravenous 5-FU regimens while minimizing hospital visits. Due to its wide range of side effects, close monitoring and personalized dose adjustments are crucial.