Phoxelon, with the active ingredient Cyclophosphamide, is an alkylating agent used primarily in cancer treatment and as an immunosuppressive drug. It works by damaging DNA in rapidly dividing cells, leading to their death. Cyclophosphamide is highly versatile and is used in oncology and autoimmune disease management. 

Uses

Cancers:

• Breast cancer
• Ovarian cancer
• Non-Hodgkin's lymphoma
• Hodgkin's lymphoma
• Multiple myeloma
• Leukemia
• Small cell lung cancer

Autoimmune diseases:

• Severe rheumatoid arthritis
• Systemic lupus erythematosus
• Nephrotic syndrome

Cyclophosphamide is a prodrug converted in the liver to its active form. It cross-links DNA strands, inhibiting DNA replication and transcription, leading to cell death, particularly in rapidly dividing cells like cancer and immune cells.

Onset and Duration of Action

• Onset of Action: Therapeutic effects are seen within days to weeks, depending on the condition.
• Duration of Action: Effects can persist for weeks to months after discontinuation due to its impact on cell cycles.

Side Effects
Common side effects include:

• Nausea and vomiting
• Alopecia (hair loss)
• Myelosuppression (low blood counts)
• Hemorrhagic cystitis (bladder inflammation)
• Increased risk of infections
• Infertility (may be permanent)

Rare but severe side effects:

• Secondary malignancies (e.g., leukemia)
• Severe liver or cardiac toxicity

Precautions

• Regular monitoring of complete blood counts and renal/liver function.
• Adequate hydration and frequent urination to reduce bladder toxicity.
• Avoid live vaccines during treatment.
• Use contraception during and after treatment (both males and females).

Contraindications

• Severe bone marrow suppression
• Active infections
• Known hypersensitivity to cyclophosphamide
• Pregnancy and breastfeeding

Drug Interactions

• Increased risk of bone marrow suppression with other cytotoxic drugs.
• Enhanced cardiotoxicity with anthracyclines (e.g., doxorubicin).
• Interaction with allopurinol may increase toxicity.

Dosage and Administration

Formulation: Injectable and oral forms

Dosage:

• Cancer therapy: Typically 500-1,500 mg/m² IV every 3 weeks or 50-100 mg/m² orally daily, depending on the regimen.
• Autoimmune diseases: 1-3 mg/kg orally daily or 500-1,000 mg IV monthly.

Administration: Ensure adequate hydration to prevent bladder toxicity (hemorrhagic cystitis).