The taxoids: paclitaxel (Taxol) and docetaxel (Taxotere)

The taxoids, paclitaxel (Taxol) and docetaxel (Taxotere), represent a novel class of antineoplastic drugs. Paclitaxel and docetaxel share a similar mechanism of action: the promotion of microtubule assembly and inhibition of microtubule disassembly. The clinical development of paclitaxel was initially hampered by hypersensitivity reactions (HSRs). The use of premedications and prolongation of the infusion time to 24h has reduced these reactions and allowed this drug's clinical development. Although paclitaxel's clinical activity has not been fully investigated, clinical trials have demonstrated its activity against ovarian, breast, and bronchial carcinomas. Because phase I studies of docetaxel noted occasional HSRs and these observations increased with further clinical experiences, those premedications employed with paclitaxel have now been instituted in many phase II studies of docetaxel. Docetaxel is currently being investigated in ovarian, breast, and bronchial carcinomas and has shown impressive clinical activity. The dose-limiting toxicity of both these agents is neutropenia; myalgias, mucositis, neuropathies, and alopecia have also been observed with both drugs. Additionally, a fluid retention syndrome and cutaneous toxicities have been noted in patients treated with docetaxel. Future studies of the taxoids will allow further comparisons of the toxicity and efficacy of these agents.