Epipodophyllotoxins

EPIPODOPHYLLOTOXINS

Etoposide is a semisynthetic derivative of podophyllotoxin, whichis extracted from the mayapple root (Podophyllum peltatum). Intravenous and oral formulations of etoposide are approved for clinical use in the USA. The oral bioavailability is about 50%, requiring the oral dose to be twice that of an intravenous dose. Up to 30–50% of drug is excreted in the urine, and dose reduction is required in the setting of renal dysfunction. The main site of action is inhibition of the DNA enzyme topoisomerase II. Etoposide has clinical activity in germ cell cancer, small cell and non-small cell lung cancer, Hodgkin’s and non-Hodgkin’s lym-phomas, and gastric cancer. In addition, it is effective in high-dose regimens in the transplant setting for breast cancer and lympho-mas. Major toxicities are listed in Table 54–4.