Capecitabine is an oral prodrug of 5-fluorouracil (5-FU), a pyrimidine analogue antimetabolite. It is a cornerstone of chemotherapy for gastrointestinal and breast cancers in India, valued for its oral administration which improves patient convenience and reduces hospital visits. It undergoes a three-step enzymatic conversion to its active form, 5-FU, preferentially within tumor tissues.
Adult: Standard monotherapy dose: 1250 mg/m² orally twice daily (morning and evening) for 2 weeks, followed by a 1-week rest period. This constitutes one 3-week cycle. Doses are typically rounded to the nearest 500mg or 150mg tablet strength for accurate administration.
Note: Take WITH FOOD (within 30 minutes after a meal) with a full glass of water to reduce gastrointestinal irritation and improve tolerability. Tablets should be swallowed whole, not crushed or split. Doses are taken approximately 12 hours apart. Adhere strictly to the 2-weeks-on, 1-week-off schedule.
Capecitabine is a prodrug that is enzymatically converted to 5-fluorouracil (5-FU) preferentially in tumor tissue. 5-FU is then metabolized to active nucleotides: fluorodeoxyuridine monophosphate (FdUMP) and fluorouridine triphosphate (FUTP). FdUMP inhibits thymidylate synthase (TS), a key enzyme for de novo thymidine synthesis, leading to impaired DNA synthesis and repair. FUTP is incorporated into RNA, interfering with RNA processing and function.
Pregnancy: Pregnancy Category D (US FDA). Can cause fetal harm. Based on mechanism and animal data, it is teratogenic and embryotoxic. Effective contraception is required during and for at least 6 months after treatment for both male and female patients. Not recommended during pregnancy.
Driving: Fatigue, dizziness, and rarely neurotoxicity may impair the ability to drive or operate machinery. Patients should be cautioned.
| Warfarin | Capecitabine may significantly increase INR and risk of bleeding. Mechanism: possibly inhibition of CYP2C9. | High |
| Phenytoin | Capecitabine may increase phenytoin levels, leading to toxicity. Monitor phenytoin levels closely. | High |
| Leucovorin (Folinic Acid) | Potentiates the cytotoxicity and toxicity of capecitabine/5-FU. Used therapeutically in some regimens but increases risk of severe diarrhea. | Moderate |
| Allopurinol | May decrease the efficacy of capecitabine by interfering with its activation pathway. Generally not recommended for concurrent use. | Moderate |
| Antacids (Aluminum/Magnesium hydroxide) | May alter gastric pH and potentially affect absorption. Administer capecitabine at least 2 hours apart. | Low |