Harvesting bark of yew tree
Paclitaxel (US brand name: Taxol) is a chemotherapy agent extracted from Taxus brevifolia (a Pacific yew tree). It inhibits cell division by binding to tubulin and preventing the disassembly of microtubules, and it also induces cell death (apoptosis) by blocking the ability of the protein Bcl-2 to prevent apoptosis1.
Drug profile
- Class: Cytotoxic antimicrotubule agent
- Mechanism of action: Paclitaxel inhibits the G2 phase of the cell cycle, preventing replication by promoting the creation of microtubules from tubulin dimers. It can also cause damage to the cell's chromosome.
- Treatment type: Chemotherapy
- US approval: 1992
- Synonyms: Taxol
- FDA Use-in-Pregnancy Rating: Category D
What Paclitaxel is effective for and why
Paclitaxel is indicated for use against ovarian cancer, breast cancer, some types of lung cancer, and a cancer of the skin and mucous membranes called Kaposi's sarcoma typically found in patients with AIDS2. This agent also has a number of off-label indications, as it is sometimes used in the treatment of other cancers, including head and neck cancers, esophagus cancer, bladder cancer, cervical cancer, and cancer of the endometrium.3
In order to facilitate drug delivery, paclitaxel is dissolved in a solvent known as Cremophor EL; this solvent is responsible for a good portion of the drug's toxicity profile. It should be noted that another breast cancer drug, Abraxane (which, unlike paclitaxel, is not available as a generic) is merely paclitaxel reformulated without this solvent.4
Paclitaxel side effects: Overview
Paclitaxel has been in use for almost two decades, so its safety and efficacy profiles are rather well established. The same is true for the side effects, which are in general pain or irritation at the injection site, weakness, nausea, vomiting, diarrhea, hair loss and mouth sores. More serious, and more uncommon, side effects of paclitaxel include neuropathy, extreme fatigue, bruising or bleeding, chest pain, blistering skin, or an irregular heartbeat.5
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