Paclitaxel (taxol).

Paclitaxel is a novel antineoplastic that effects cytotoxicity by promoting intracellular tubulin polymerization and stabilizes abnormal microtubule structures against depolymerization. Although its clinical development had been hampered by misconceptions about its pharmacology, its scarcity, difficulties extracting it from its natural source, formulation problems, and frequent severe hypersensitivity reactions, paclitaxel recently was approved for treatment-refractory ovarian cancer. Two major adverse effects are dosage- and schedule-related myelosuppression and mucositis. Neurotoxicity is directly related to both the individual and cumulative doses. Other relevant toxicities are hypersensitivity reactions, effects on cardiac rate and rhythm, arthralgias and myalgias, generalized hair loss, and mild nausea and emesis. Continuing clinical studies will evaluate paclitaxel as initial therapy for ovarian cancer and its utility in other malignancies. In addition, major efforts are under way to develop alternative sources to increase the availability of taxene analogs and reduce our dependence on yew species.