Citabin by BDR Pharmaceuticals contains Capecitabine, an oral prodrug of 5-fluorouracil (5-FU), used in the treatment of various cancers. Capecitabine is designed to selectively activate in tumor tissues, reducing systemic side effects and enhancing therapeutic efficacy. 

Composition:

• Active Ingredient: Capecitabine 500 mg.

• Form: Film-coated tablet.

• Route of Administration: Oral.

Indications:

Colorectal Cancer:

• Treatment for metastatic colorectal cancer.

• Adjuvant therapy for patients with Dukes' C colon cancer after surgery.

Breast Cancer:

• Treatment of locally advanced or metastatic breast cancer.

• Commonly used in combination with docetaxel after anthracycline-based chemotherapy failure.

Gastric Cancer:

• Used in advanced gastric cancer, often in combination with platinum-based regimens.

Off-Label Uses:

• Sometimes prescribed for other solid tumors under clinical discretion.

Mechanism of Action:

Capecitabine is converted enzymatically into 5-fluorouracil (5-FU) within tumor cells. The active metabolite interferes with DNA synthesis by:

1. Inhibiting thymidylate synthase, which blocks thymidine production needed for DNA replication.

2. Disrupting RNA and protein synthesis, ultimately leading to cancer cell death.

This tumor-selective activation minimizes systemic toxicity.

Side Effects:

Common Side Effects:

1. Nausea and vomiting

2. Diarrhea

3. Hand-foot syndrome (palmar-plantar erythrodysesthesia)

4. Fatigue

5. Mucositis

6. Anorexia

Serious Side Effects:

1. Cardiotoxicity: Rare events such as myocardial infarction or arrhythmias.

2. Hematological Toxicity: Neutropenia, thrombocytopenia, anemia.

3. Severe Diarrhea: Can lead to dehydration; requires immediate attention.

4. Skin Reactions: Rare but may include Stevens-Johnson syndrome or toxic epidermal necrolysis.

Precautions:

Renal Impairment:

• Dose reductions necessary in patients with moderate renal dysfunction.

• Avoid use in severe renal impairment (CrCl <30 mL/min).

Hepatic Dysfunction:

• Use cautiously in patients with liver impairment, as metabolism may be altered.

Cardiac Conditions:

• Monitor for ischemia or arrhythmias in patients with pre-existing heart disease.

Pregnancy and Lactation:

• Contraindicated in pregnancy due to teratogenic risks.

• Breastfeeding is not recommended during treatment.

Monitoring Requirements:

• Regular monitoring of blood counts, liver enzymes, and renal function is essential.

• Assess for signs of toxicity, particularly gastrointestinal and hematologic adverse effects.

Contraindications:

Hypersensitivity:

• Allergy to Capecitabine, fluorouracil, or any excipient in the tablet.

Severe Renal Impairment:

• Contraindicated in patients with creatinine clearance <30 mL/min.

Dihydropyrimidine Dehydrogenase (DPD) Deficiency:

• Patients with complete DPD deficiency are at risk of severe toxicity.

Pregnancy and Lactation:

• Contraindicated due to potential harm to the fetus or breastfeeding infant.

Drug Interactions:

Anticoagulants (e.g., Warfarin):

• Increased risk of bleeding; monitor INR levels closely.

Phenytoin:

• Increased serum levels; monitor for signs of toxicity.

Folic Acid and Folate Derivatives:

• Can enhance Capecitabine’s cytotoxic effects.

Allopurinol:

• May reduce the efficacy of Capecitabine.

Leucovorin:

• Increases the toxicity of Capecitabine; use cautiously.

Dosage and Administration:

Colorectal Cancer:

• Dosage: 1250 mg/m² orally twice daily for 14 days, followed by a 7-day rest period (21-day cycle).

Breast Cancer (Monotherapy):

• Dosage: 1250 mg/m² orally twice daily for 14 days, followed by a 7-day rest period.

Combination Therapy (e.g., with Docetaxel):

• Dosage: 1000 mg/m² orally twice daily for 14 days, followed by a 7-day rest period.

Special Populations:

• Renal Impairment: Dose adjustments required for creatinine clearance <50 mL/min.

• Elderly Patients: Higher sensitivity to side effects; dose adjustment may be needed.

Administration Instructions:

• Take with water 30 minutes after a meal.

• Do not crush or split the tablets.

Onset of Action:

• The anticancer effects may become noticeable after several cycles, depending on the cancer type and progression.

Duration of Action:

• The effects of Capecitabine last for the entire dosing cycle, with a half-life of approximately 45–60 minutes.

Storage Instructions:

• Store at 15–30°C (59–86°F) in a dry place.

• Protect from moisture and direct sunlight.

• Keep out of reach of children.