Topotecan

Topotecan is a chemotherapy drug that belongs to the camptothecin family. It is a semi-synthetic, water-soluble analogue of camptothecin and acts as a topoisomerase I inhibitor. By stabilizing the cleavable complex between topoisomerase I and DNA, it prevents strand religation, leading to DNA damage and cancer cell death, particularly in rapidly dividing cells.

Topotecan is administered by intravenous infusion and, in some settings, as an oral formulation. Dosing and cycle length vary by indication and regimen. The drug is cleared primarily by the kidneys, and renal impairment necessitates dose adjustment. Patients receiving topotecan require regular blood count monitoring due to its hematologic toxicity.

Indications include relapsed or refractory ovarian cancer, where it is used as a second-line therapy in certain regimens; recurrent or metastatic cervical cancer, commonly in combination with cisplatin; and relapsed small cell lung cancer after prior chemotherapy. Its use and combinations are guided by regional approvals and clinical guidelines.

Common adverse effects are hematologic, including neutropenia and thrombocytopenia, as well as anemia. Nonhematologic effects frequently include nausea, vomiting, diarrhea or constipation, fatigue, and mucositis. Less common events can involve elevated liver enzymes and hair loss. Serious risks include febrile neutropenia and infection; as with other cytotoxic agents, patients with significant renal or hepatic impairment may have higher exposure and altered toxicity risk.

Pharmacology notes: topotecan is often given in cycles, with dose adjustments for renal function. It is used within a framework of combination therapies depending on cancer type and patient status. Brand-name mention includes Hycamtin.