n. a *cytotoxic drug derived from an extract of the mandrake plant that interferes with DNA replication (see topoisomerase inhibitor). It is used mainly in the treatment of bronchial carcinoma, lymphomas, and testicular tumours. Side-effects include alopecia, nausea, and marrow suppression.
any one of a class of *cytotoxic drugs that work by blocking the action of topoisomerase enzymes, which promote the uncoiling of the DNA double helix, a necessary preliminary to replication. Topoisomerase I inhibitors include irinotecan, used for treating advanced colorectal cancer (especially in combination with *fluorouracil); and topotecan, given for treating advanced ovarian cancer, relapsed small-cell lung cancer, and recurrent cervical cancer. Side-effects include delayed but severe diarrhoea and reduction in blood-cell production by the bone marrow. Topoisomerase II inhibitors include *etoposide and *doxorubicin.... topoisomerase inhibitor