etoposide

Etoposide is a chemotherapy agent used to treat a range of cancers. It is a semisynthetic derivative of podophyllotoxin and belongs to the epipodophyllotoxin class. Etoposide inhibits topoisomerase II, stabilizing the enzyme-DNA complex and causing DNA double-strand breaks during replication. The resulting DNA damage induces apoptosis in rapidly dividing cells.

Medical uses include treatment of testicular cancer in combination regimens such as BEP (bleomycin, etoposide, cisplatin), as well as small cell lung cancer, lymphomas, germ cell tumors, and certain leukemias. It is also used in pediatric cancers and in high-dose regimens with stem cell support. Etoposide is available as an intravenous infusion and as an oral formulation, though oral bioavailability is variable and influenced by food and timing with meals.

Pharmacokinetics: after administration, etoposide is partially metabolized in the liver to active and inactive metabolites and is excreted in urine and to a lesser extent in feces. The elimination half-life varies between individuals, typically several hours; dosing may be adjusted in hepatic or renal impairment. Caution is advised in elderly patients and those with organ dysfunction.

Adverse effects: the most common toxicity is myelosuppression, especially neutropenia and thrombocytopenia, which increases infection and bleeding risk. Other frequent effects include nausea, mucositis, alopecia, and fatigue. Infusion-related reactions and hypersensitivity can occur. There is a known risk of secondary leukemia (therapy-related AML) with cumulative doses. Etoposide is teratogenic; pregnancy should be avoided. Proper monitoring and dose adjustment are essential to manage toxicity.