Ovarian Cancer: Topotecan injection is used as a single-agent therapy for patients with metastatic ovarian cancer whose disease has progressed after initial or subsequent chemotherapy.

Small Cell Lung Cancer: Topotecan injection is indicated as a single-agent treatment for patients with small cell lung cancer who are sensitive to platinum-based therapy and whose disease has progressed at least 60 days after starting first-line chemotherapy.

Cervical Cancer: Topotecan, in combination with cisplatin, is used for patients with Stage IV-B, recurrent, or persistent cervical cancer that cannot be treated with curative intent.

Topotecan works similarly to irinotecan and exerts its cytotoxic effects during the S-phase of DNA replication. It targets the enzyme topoisomerase I, which normally helps relieve DNA strain by creating temporary single-strand breaks.
Topotecan binds to the topoisomerase I-DNA complex and prevents the repair (religation) of these breaks. This interference disrupts DNA replication, leading to replication arrest and the formation of irreversible double-strand DNA breaks. Since cells cannot effectively repair these damages, it ultimately results in programmed cell death (apoptosis).

Additionally, Topotecan intercalates between DNA base pairs at the cleavage site, blocking DNA repair and acting as an uncompetitive inhibitor of the enzyme.

Verify dose using body surface area prior to dispensing. Recommended dosage should generally not exceed 4 mg intravenously

Ovarian Cancer: The recommended dose of Topotecan is 1.5 mg/m² by intravenous infusion over 30 minutes daily for 5 consecutive days, starting on Day 1 of a 21-day course.

Small Cell Lung Cancer: The recommended dose of Topotecan is 1.5 mg/m² by intravenous infusion over 30 minutes daily for 5 consecutive days, starting on Day 1 of a 21-day course.

Cervical Cancer: The recommended dose of Topotecan is 0.75 mg/m² by intravenous infusion over 30 minutes daily on Days 1, 2, and 3 in combination with cisplatin 50 mg/m² on Day 1, repeated every 21 days.

Topotecan clearance may be increased when used with phenytoin. Granulocyte-colony stimulating factor (G-CSF) should be administered at least 24 hours after completing Topotecan therapy, as concurrent use may prolong neutropenia.
Coadministration with other cytotoxic drugs (such as cisplatin) may enhance bone marrow suppression, and dose adjustment may be required.

Topotecan is contraindicated in patients with severe bone marrow suppression (e.g., neutrophil count <1500 cells/mm³ and platelet count <100,000/mm³). It is also contraindicated during pregnancy, lactation, and in patients with severe renal or hepatic impairment.

Common side effects include neutropenia (lowest white blood cell count usually occurs 9–12 days after administration), thrombocytopenia, and anemia. Other effects may include gastrointestinal disturbances, complete hair loss, headache, shortness of breath, fatigue, weakness, malaise, itching, and elevated bilirubin levels.

Topotecan is classified as Pregnancy Category D, indicating evidence of fetal risk. However, its use may be considered in life-threatening conditions or serious diseases where safer alternatives are not effective.

Patients with preexisting bone marrow suppression require careful monitoring. Regular blood cell count assessments are essential during treatment.
Further treatment cycles should not be started until neutrophil count exceeds 1000 cells/mm³, platelet count exceeds 100,000/mm³, and hemoglobin level reaches at least 9 g/dL (with transfusion if necessary).
Topotecan may impair the ability to drive or operate machinery.

Renal Impairment:

• Ovarian cancer / Small cell lung cancer: If creatinine clearance (CrCl) is 20–30 mL/min, initial dose should be 0.75 mg/m².
• Cervical cancer: Treatment should only begin if serum creatinine is ≤1.5 mg/dL.

Hepatic Impairment: Use is not recommended in patients with severe hepatic impairment.

Overdose primarily results in bone marrow suppression.

Cytotoxic chemotherapy

Add 4 mL of sterile water for injection to a vial containing 4 mg Topotecan to prepare a solution of 1 mg/mL. The required dose should then be diluted in 50–250 mL of 5% dextrose or 0.9% sodium chloride and administered intravenously over 30 minutes. The solution should be prepared immediately before use.