Xeloda

The dosage of Capecitabine is highly individualized and is calculated based on a patient's Body Surface Area (BSA), which is determined by height and weight.

• Standard Monotherapy Dose: The typical starting dose is 1250 mg/m² administered orally twice daily (morning and evening; equivalent to 2500 mg/m² total daily dose).
• Treatment Cycle: This is usually administered in a '3-week cycle.' The patient takes the medication for 14 consecutive days (2 weeks), followed by a 7-day (1 week) rest period where no medication is taken.
• Combination Therapy: When used with other drugs like docetaxel or oxaliplatin, the starting dose of Capecitabine may be reduced (e.g., to 800 mg/m² to 1000 mg/m² twice daily) to manage the cumulative toxicity of multiple chemotherapy agents.

The safety and effectiveness of Capecitabine in pediatric patients (under the age of 18) have not been established. There are currently no FDA-approved indications for Capecitabine in children. Clinical trials in pediatric populations are limited, and use in this group would be considered highly experimental and only under strict clinical trial protocols.

Renal Impairment

Kidney function is critical for the clearance of Capecitabine metabolites.

• Mild Impairment (CrCl 51-80 mL/min): No adjustment is usually required, but close monitoring for side effects is necessary.
• Moderate Impairment (CrCl 30-50 mL/min): The starting dose is typically reduced to 75% of the standard dose (a 25% reduction).
• Severe Impairment (CrCl < 30 mL/min): Capecitabine is strictly contraindicated (must not be used) in these patients due to the risk of severe, potentially fatal toxicity.

Hepatic Impairment

While the liver is responsible for the first step of activation, studies in patients with mild-to-moderate liver impairment due to liver metastases showed that no initial dose adjustment is required. However, these patients must be monitored very closely for toxicity, as liver function can change rapidly during cancer treatment.

Elderly Patients

Patients over the age of 60 are at a significantly higher risk for severe gastrointestinal toxicity (nausea, vomiting, diarrhea) and Hand-Foot Syndrome. Physicians often start elderly patients at a reduced dose or monitor them with extreme frequency, especially during the first two cycles of treatment.

1. 1Timing: Take the dose within 30 minutes after finishing a meal (breakfast and dinner). Food is necessary to ensure the drug is absorbed correctly.
2. 2Administration: Swallow the tablets whole with a full glass of water (approximately 8 ounces). Do not crush, chew, or split the tablets, as this can alter the absorption and increase the risk of side effects or environmental contamination.
3. 3Consistency: Try to take your doses approximately 12 hours apart at the same times each day to maintain steady levels of the drug in your bloodstream.
4. 4Handling: If a caregiver is assisting with the medication, they should wear disposable gloves. Wash hands thoroughly after handling the tablets.
5. 5Storage: Store at room temperature (68°F to 77°F) in a dry place. Keep the bottle tightly closed and away from children and pets.

If you miss a dose of Capecitabine, do not take the missed dose when you remember. Skip the missed dose entirely and wait until your next scheduled dose time. Never double the dose to make up for a missed one. Chemotherapy requires precise levels; taking too much at once can lead to severe toxicity. Inform your oncology team if you miss more than one dose.

Signs of a Capecitabine overdose may include severe nausea, vomiting, diarrhea, gastrointestinal bleeding, bone marrow suppression (leading to infection or bruising), and severe skin reactions.

In the event of a suspected overdose, contact your local poison control center or seek emergency medical attention immediately. Treatment is primarily supportive, focusing on managing symptoms and preventing dehydration or infection.

> Important: Follow your healthcare provider's dosing instructions exactly. Do not adjust your dose or stop taking the medication without medical guidance, even if you feel better or experience side effects.

Capecitabine is associated with several frequent side effects that patients should be prepared to manage in coordination with their medical team:

• Hand-Foot Syndrome (Palmar-Plantar Erythrodysesthesia): This is the most characteristic side effect. It starts as numbness, tingling, or redness of the palms and soles. It can progress to painful swelling, blistering, and peeling.
• Diarrhea: This can range from mild to life-threatening. Patients must track the number of stools per day. Dehydration is a major risk associated with Capecitabine-induced diarrhea.
• Nausea and Vomiting: Usually manageable with anti-nausea medications, but can lead to poor nutritional intake.
• Fatigue: A profound sense of tiredness that does not always improve with rest.
• Abdominal Pain: General discomfort or cramping in the stomach area.
• Stomatitis (Mouth Sores): Painful sores or redness in the mouth and throat, making eating and drinking difficult.

• Myelosuppression: A decrease in blood cell production, leading to anemia (low red cells), leukopenia (low white cells/increased infection risk), and thrombocytopenia (low platelets/increased bruising).
• Dermatitis: Dry, itchy, or flaky skin across the body.
• Hyperbilirubinemia: An increase in bilirubin in the blood, which may cause a yellowish tint to the skin or eyes (jaundice).
• Eye Irritation: Increased tearing, redness, or a 'gritty' feeling in the eyes.
• Neurological Effects: Dizziness, headache, or insomnia.

• Cardiotoxicity: This includes chest pain (angina), heart rhythm changes, or even heart attacks. This is more common in patients with a history of heart disease.
• Hepatic Failure: Severe liver damage, characterized by extreme jaundice and confusion.
• Lacrimal Duct Stenosis: Permanent scarring of the tear ducts.
• Severe Allergic Reactions: Anaphylaxis or severe skin reactions like Stevens-Johnson Syndrome (SJS).

> Warning: Stop taking Capecitabine and call your doctor immediately if you experience any of these symptoms. These are signs of severe toxicity that may require hospitalization.

1. 1Diarrhea: An increase of 4 or more bowel movements per day over your normal baseline, or diarrhea at night.
2. 2Vomiting: If you vomit more than once in a 24-hour period.
3. 3Nausea: Loss of appetite or eating much less than usual.
4. 4Stomatitis: Painful redness, swelling, or ulcers in the mouth or throat.
5. 5Hand-Foot Syndrome: Painful redness, swelling, or ulcers on the hands or feet that prevent normal activity.
6. 6Fever: A temperature of 100.5°F (38°C) or higher, which may indicate a life-threatening infection.
7. 7Chest Pain: Any new or worsening chest pressure or pain, which could indicate a heart issue.

While many side effects resolve after the drug is stopped, some long-term effects may persist:

• Hyperpigmentation: Darkening of the skin or nails that may take months to fade.
• Tear Duct Damage: Some patients may experience chronic watery eyes due to permanent changes in the tear ducts.
• Peripheral Neuropathy: Persistent numbness or tingling in the extremities, though this is less common with Capecitabine than with other chemotherapies like oxaliplatin.

Warfarin Interaction Warning: Capecitabine has a significant interaction with warfarin (Coumadin). It can dramatically increase the blood-thinning effects of warfarin, leading to life-threatening bleeding or hemorrhage. This can occur within days of starting Capecitabine and up to a month after stopping it. Patients taking warfarin must have their PT/INR (clotting tests) monitored very frequently.

Report any unusual symptoms or changes in your health to your healthcare provider immediately. Early intervention is the key to continuing Capecitabine therapy safely.

Capecitabine is a high-potency cytotoxic medication. It must only be prescribed by a physician experienced in the use of antineoplastic agents. Patients must be educated on the 'Stop Rules'—knowing exactly when to hold a dose if toxicity occurs. Because Capecitabine is an oral medication, the responsibility for monitoring daily side effects falls largely on the patient and their caregiver. Failure to stop the medication at the first sign of moderate toxicity can lead to rapid clinical deterioration.

Interaction with Warfarin (Coumadin): The FDA has issued a Black Box Warning regarding the use of Capecitabine in patients taking warfarin. Clinical trials and post-marketing reports have shown clinically significant increases in prothrombin time (PT) and International Normalized Ratio (INR) in patients receiving both drugs. This interaction can lead to fatal bleeding episodes. If co-administration is absolutely necessary, INR must be monitored with extreme frequency (often several times a week), and the warfarin dose must be adjusted accordingly.

• DPD Deficiency: Dihydropyrimidine dehydrogenase (DPD) is the enzyme that breaks down 5-FU. Approximately 3-5% of the population has a partial DPD deficiency, and 0.2% has a complete deficiency. Patients with this genetic trait cannot metabolize Capecitabine, leading to toxic levels of the drug. This can result in life-threatening complications, including severe enterocolitis (bowel inflammation) and profound bone marrow failure.
• Cardiotoxicity: Like other fluoropyrimidines, Capecitabine can cause cardiotoxicity. This includes myocardial infarction (heart attack), angina (chest pain), dysrhythmias, cardiogenic shock, and sudden death. Patients with pre-existing coronary artery disease are at higher risk.
• Dehydration and Renal Failure: Diarrhea can rapidly lead to dehydration, which in turn causes acute renal (kidney) failure. This is particularly dangerous in elderly patients. If you cannot keep fluids down or have severe diarrhea, you may need intravenous fluids in a hospital setting.
• Severe Skin Reactions: Rarely, Capecitabine can cause Stevens-Johnson Syndrome (SJS) or Toxic Epidermal Necrolysis (TEN). These are medical emergencies characterized by a painful rash that blisters and peels.

Your doctor will require regular laboratory tests to ensure the drug is not causing hidden damage:

• Complete Blood Count (CBC): To monitor white blood cells, red blood cells, and platelets. Usually checked before every 3-week cycle.
• Liver Function Tests (LFTs): To monitor bilirubin and liver enzymes (AST/ALT).
• Renal Function (Creatinine/BUN): To ensure the kidneys are clearing the drug's metabolites effectively.
• INR/PT: Only for patients on anticoagulants like warfarin.

Capecitabine may cause dizziness, fatigue, or nausea. If you experience these symptoms, you should avoid driving or operating heavy machinery until the symptoms resolve. Most patients can drive normally, but caution is advised during the first cycle of treatment when you do not yet know how your body will react to the drug.

While there is no direct contraindication between alcohol and Capecitabine, alcohol can worsen certain side effects. Alcohol can irritate the lining of the mouth and gastrointestinal tract, potentially worsening stomatitis and diarrhea. It can also contribute to dehydration. It is generally recommended to limit alcohol intake during chemotherapy.

Capecitabine does not require a tapering period (gradually reducing the dose). It can be stopped abruptly if toxicity occurs. In fact, the standard protocol for managing side effects is the 'Hold and Restart' method: the drug is stopped until the side effect resolves to Grade 0 or 1, and then restarted, often at a lower dose. Do not stop the drug for more than a day without informing your oncologist, as this may affect the efficacy of your cancer treatment.

> Important: Discuss all your medical conditions, especially heart disease, kidney disease, or a known DPD deficiency, with your healthcare provider before starting Capecitabine.

• Sorivudine and Analogs: Sorivudine is an antiviral medication. Using it with Capecitabine is strictly contraindicated because it inhibits the enzyme that breaks down 5-FU, leading to a massive, potentially fatal increase in Capecitabine toxicity. A washout period of at least 4 weeks is required between these medications.
• Allopurinol: Some studies suggest allopurinol may decrease the efficacy of 5-FU (the active form of Capecitabine). Co-administration should generally be avoided unless deemed essential by your oncologist.

• Warfarin (Coumadin): As noted in the Black Box Warning, this is a critical interaction. Capecitabine inhibits the CYP2C9 enzyme system, which is responsible for metabolizing warfarin. This causes warfarin levels to spike, leading to severe bleeding risk.
• Phenytoin (Dilantin): Capecitabine can increase the levels of phenytoin in the blood, potentially leading to phenytoin toxicity (symptoms include ataxia, confusion, and slurred speech). Phenytoin levels must be monitored closely.
• Leucovorin (Folinic Acid): Leucovorin is often given with 5-FU to increase its efficacy. However, it also increases the toxicity of Capecitabine. While sometimes used together intentionally in specific regimens, the combination requires very careful monitoring for severe diarrhea and skin reactions.

• Antacids: Antacids containing aluminum hydroxide or magnesium hydroxide (like Maalox or Mylanta) can slightly increase the absorption of Capecitabine. While not strictly forbidden, they should be taken with caution, and your doctor should be aware of their use.
• CYP2C9 Substrates: Since Capecitabine inhibits CYP2C9, other drugs processed by this enzyme may have increased levels in the body.

• Food Requirement: Capecitabine must be taken with food (within 30 minutes after a meal). Taking it on an empty stomach significantly changes how the drug is absorbed and can lead to decreased efficacy or increased side effects.
• Grapefruit Juice: While not as heavily studied as with other drugs, grapefruit juice can inhibit certain enzymes in the gut and liver. It is best to avoid large amounts of grapefruit juice while on chemotherapy to ensure predictable drug levels.

• St. John's Wort: This herbal supplement is a potent inducer of liver enzymes and can potentially lower the concentration of Capecitabine in the blood, making the cancer treatment less effective.
• Folic Acid Supplements: High doses of folic acid (found in many multivitamins) can act similarly to leucovorin and may increase the toxicity of Capecitabine. Patients should discuss all vitamin intake with their oncologist; a standard daily multivitamin is usually acceptable, but high-dose supplements should be avoided.

• Bilirubin: Capecitabine can cause a false or drug-induced elevation in serum bilirubin, which may not always indicate liver damage but requires clinical evaluation.
• Blood Glucose: Some patients may experience slight elevations in blood glucose levels while taking Capecitabine.

For each major interaction, the primary concern is either the increase in toxicity (making the drug dangerous) or the reduction in efficacy (making the cancer treatment fail). Management usually involves dose adjustment, increased monitoring, or choosing an alternative medication.

> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking, including over-the-counter pain relievers and vitamins.

There are several scenarios where Capecitabine must never be used because the risks far outweigh any potential benefits:

1. 1Known DPD Deficiency: Patients with a complete deficiency of the dihydropyrimidine dehydrogenase (DPD) enzyme are at risk for catastrophic, life-threatening toxicity from even standard doses of Capecitabine.
2. 2Severe Renal Impairment: If the creatinine clearance (CrCl) is less than 30 mL/min, the body cannot clear the metabolites of Capecitabine. This leads to a rapid buildup of the drug and severe systemic poisoning.
3. 3Hypersensitivity: If a patient has had a severe allergic reaction to Capecitabine, 5-fluorouracil, or any of the inactive ingredients in the tablet (such as lactose), they must not take the drug.
4. 4Co-administration with Sorivudine: Due to the risk of fatal drug-drug interaction, these two must never be taken together.

These conditions require a careful risk-benefit analysis by the oncologist:

• Mild to Moderate Renal Impairment (CrCl 30-50 mL/min): Requires a mandatory 25% dose reduction and weekly monitoring.
• History of Heart Disease: Patients with a history of arrhythmia, angina, or heart failure must be monitored with baseline and periodic EKGs, as Capecitabine can trigger cardiac events.
• Elderly Patients (Age >70): Due to the high incidence of severe GI toxicity and dehydration, the 'starting' dose is often debated and monitored with extreme care.
• Active Infection: Chemotherapy can suppress the immune system, making it difficult to fight off an existing infection. Infections should ideally be treated before starting a new cycle.

Patients who have experienced severe toxicity or allergic reactions to 5-fluorouracil (5-FU) (often given as an IV infusion like Adrucil) are highly likely to have the same reaction to Capecitabine. Because Capecitabine is a prodrug of 5-FU, the active molecule is identical. If you have ever had a 'bad reaction' to IV chemotherapy for colon or breast cancer, it is vital to tell your doctor the name of that drug.

> Important: Your healthcare provider will evaluate your complete medical history, including genetic testing for DPD deficiency in some cases, before prescribing Capecitabine.

FDA Pregnancy Category D: Capecitabine can cause fetal harm when administered to a pregnant woman. In animal studies, Capecitabine was found to be teratogenic (causing birth defects) and embryolethal (causing fetal death) at doses lower than the human therapeutic dose.

• Women of Childbearing Potential: Must use highly effective contraception during treatment and for at least 6 months after the final dose.
• Men with Female Partners: Because Capecitabine can affect sperm, men should use effective contraception during treatment and for 3 months after the final dose.
• Trimester Risks: Exposure during the first trimester carries the highest risk for major structural malformations.

It is not known whether Capecitabine or its metabolites are excreted in human breast milk. However, because many drugs are excreted in milk and because of the potential for serious adverse reactions in nursing infants, women are advised to discontinue breastfeeding during treatment with Capecitabine and for at least 2 weeks after the final dose.

Capecitabine is not approved for use in children. The pharmacokinetics and safety profile in pediatric patients have not been established. In the rare instances where it is used (e.g., specific pediatric brain tumors), it is done so only within the context of a controlled clinical trial at a specialized pediatric oncology center.

Patients over 65 years of age are at an increased risk for Grade 3 or 4 toxicities compared to younger patients. Specifically:

• Gastrointestinal Toxicity: Higher rates of severe diarrhea, nausea, and vomiting.
• Skin Toxicity: Increased severity of Hand-Foot Syndrome.
• Pharmacokinetics: While the drug's processing doesn't change significantly with age alone, the natural decline in kidney function that comes with aging means that many elderly patients require dose reductions.

As the kidneys are the primary route of elimination for the inactive but potentially toxic metabolite FBAL (fluoro-beta-alanine), renal function is the most important factor in Capecitabine safety.

• CrCl 51-80 mL/min: Standard dose, close monitoring.
• CrCl 30-50 mL/min: Reduce dose by 25%.
• CrCl < 30 mL/min: Do not use.

Physicians use the Cockcroft-Gault equation to calculate CrCl before every cycle.

Patients with mild-to-moderate hepatic dysfunction due to liver metastases do not typically require an initial dose adjustment. However, Capecitabine has not been adequately studied in patients with severe hepatic impairment (e.g., cirrhosis), and such patients should be treated with extreme caution.

> Important: Special populations require individualized medical assessment and more frequent laboratory monitoring to ensure safety.

Capecitabine is a fluoropyrimidine carbamate. It is a systemic prodrug of 5-fluorouracil (5-FU). The molecule is designed to be stable during gastrointestinal absorption but undergoes a three-step enzymatic conversion to 5-FU. The final step is catalyzed by thymidine phosphorylase (TP). TP is significantly more active in many tumor tissues compared to normal tissues, which allows for the preferential release of 5-FU within the tumor microenvironment. Once converted, 5-FU inhibits DNA synthesis and slows tumor growth by inhibiting thymidylate synthase and incorporating into RNA.

The cytotoxic effect of Capecitabine is schedule-dependent. Because it acts on the S-phase of the cell cycle (when DNA is being synthesized), maintaining therapeutic levels over a 14-day period is more effective than a single large dose. There is a clear dose-response relationship, but the 'therapeutic window' is narrow—meaning the dose required to kill cancer cells is very close to the dose that causes significant toxicity to the patient.

| Parameter | Value |

|---|---|

| Bioavailability | High (when taken with food) |

| Protein Binding | ~54% (primarily albumin) |

| Half-life | 0.5 to 1 hour (parent and 5-FU) |

| Tmax | 1.5 to 2 hours |

| Metabolism | Hepatic (CES1/2, CDA) and Tumor (TP) |

| Excretion | Renal 95%, Fecal <3% |

• Molecular Formula: C15H18FN3O5
• Molecular Weight: 359.35 g/mol
• Solubility: Soluble in water (26 mg/mL at 20°C), highly soluble in methanol and ethanol.
• Structure: It consists of a 5-fluorocytosine nucleus with a 5'-deoxyribose sugar and a pentyl carbamate side chain. This carbamate side chain is what makes the molecule stable and absorbable in the gut, unlike 5-FU itself.

Capecitabine is classified as an Antimetabolite and a Nucleoside Metabolic Inhibitor. It is part of the fluoropyrimidine family, which includes other drugs like 5-fluorouracil (IV) and trifluridine/tipiracil (Lonsurf). Within oncology, it is considered a 'cycle-active' cytotoxic agent.

> Important: Pharmacology data is based on the FDA-approved professional labeling and clinical pharmacokinetic studies.