Metabolized by the liver and eliminated mainly through the biliary system.
Kidney clearance is limited and renal toxicity is uncommon.
Paclitaxel and docetaxel, are highly hydrophobic and formulations include synthetic solvents to enable potential administration:
Paclitaxel contains a combination of polyethylene castor oil (Cremophor) and ethanol as the vehicle, and polysorbate 80 and an ethanol diluent are the vehicles for docetaxel.
Solvents polyethylene castor oil and polysorbate 80 directly contribute to the severe toxicities in patients with paclitaxel or docetaxel.
Solvent related toxicities include hypersensitivity reactions and peripheral neuropathy.
Solvents used may adversely affect efficacy because of entrapment of active drug in micelles formed in the plasma, with increased systemic drug exposure, with decreased drug clearance, and lack of dose dependent antitumor activity.