Docetaxel Totally Explained

Everything about Docetaxel totally explained

Docetaxel is a clinically well established anti-mitotic chemotherapy medication used mainly for the treatment of breast, ovarian, and non-small cell lung cancer. Docetaxel has an approved claim for treatment of patients who have locally advanced, or metastatic breast or non small-cell lung cancer who have undergone anthracycline-based chemotherapy and failed to stop cancer progression or relapsed. Administered as a one-hour infusion every three weeks generally over a ten cycle course, docetaxel is considered better than doxorubicin, paclitaxel and fluorouracil as a cytotoxic antimicrotubule agent.

Chemical structure, nature, and composition

Nature

Docetaxel is of the chemotherapy drug class; taxane, and is a semi-synthetic analogue of paclitaxel (Taxol), an extract from the rare Pacific yew tree Taxus brevifolia. In this T-shaped/butterfly model, a deep hydrophobic cleft exists near the surface of the β-tubulin where three potential hydrogen bonds and multiple hydrophobic contacts bind to docetaxel. The hydrophobic pocket walls contain helices H1, H6, H7 and a loop between H6 and H7 that form hydrophobic interactions with the 3’-benzamido phenyl, 3’-phenyl, and the 2-benzoyl phenyl of docetaxel. 3’-phenyl also has contact with β-sheets B8 and B10. The C-8 methyl of docetaxel has Van der Waal's interactions with two residues, Thr-276 and Gln-281 near the C-terminal end of β-tubulin. Docetaxel’s O-21 experiences electrostatic attraction to Thr-276 and the C-12 methyl has proximity with Leu-371 on the loop between B9 and B10. Oral bioavailability has been found to be 8% ±6% on its own and when co-administered with cyclosporine, bioavailability increased to 90% ± 44%. In practice, docetaxel is administered intravenously only to increase dose precision. Evaluation of docetaxel pharmacokinetics in phase II and III clinical studies were with 100 mg/m² dosages given over one-hour infusions every three weeks. Docetaxel's plasma protein binding includes lipoproteins, alpha1 acid glycoprotein and albumin. Alpha1 acid glycoprotein is the most variable of these proteins inter-individually, especially in cancer patients and is therefore the main determinant of docetaxel's plasma binding variability. Docetaxel interacted little with erythrocytes and was unaffected by the polysorbate 80 in its storage medium. Increased dose resulted in a linear increase of the area under the concentration-time curve and so it's concluded that dose is directly proportional to plasma concentration. Metabolism is principally oxidative and at the tert-butylpropionate side chain, resulting first in an alcohol docetaxel (M2), which is then cyclised to three further metabolites (M1, M3 and M4). This binding stabilises microtubules and prevents depolymerisation from calcium ions, decreased temperature and dilution, preferentially at the plus end of the microtubule. This leads to a significant decrease in free tubulin, needed for microtubule formation and results in inhibition of mitotic cell division between metaphase and anaphase, preventing further cancer cell progeny. Compared with mitoxantrone treatment, docetaxel treated patients showed a 12% overall response rate and mitoxantrone showed a 7% overall response rate. Another large advantage of docetaxel was increased quality of life. Docetaxel showed a 22% response and mitoxantrone had a 13% response. Used in conjunction with prednisone for pain management, docetaxel had a 35% response and Mitoxantrone had a 22% response. This trial leads docetaxel to be a preferred method of treatment to Mitoxantrone where possible.

Side-effects/contraindications/drug interactions

Positive side-effects

As well as inhibiting mitosis, the presence of docetaxel has been found to lead to the phosphorylation of the oncoprotein bcl-2, which leads to apoptosis of cancer cells that had previously blocked the apoptotic inducing mechanism, leading to tumour regression. This includes tumour cells as well as hair follicles, bone marrow and other germ cells. For this reason, common chemotherapy side effects such as alopecia occur.
Docetaxel is currently protected by patents (U.S. patent 4814470, European patent no EP 253738, due to expire in 2010) which are owned by Sanofi-Aventis, and so is available only under the Taxotere brand name internationally.
The Thailand Government has issued compulsory license against the patent covering Docetaxel. Indian company Dabur will supply the generic drug to Thailand. and

Clinical Trials

MD Anderson Cancer Center: A phase I/II study of Docetaxel, 5-Fluorouracil and Oxaliplatin (D-FOX) in patients with untreated locally unresectable or metastatic adenocarcinoma of the stomach or gastroesophageal junction.

Further Information

Get more info on 'Docetaxel'.

External Link Exchanges

Do you know how hard it is to get a link from a large encyclopaedia? Well we're different and will prove it. To get a link from us just add the following HTML to your site on a relevant page:

<a href="http://docetaxel.totallyexplained.com">Docetaxel Totally Explained</a>

Then simply click through this link from your web page. Our crawlers will verify your link, extract the title of your web page and instantly add a link back to it. If you like you can remove the words Totally Explained and embed the link in article text.
As long as your link remains in place, we'll keep our link to you right here. Please play fair - our crawlers are watching. Your site must be closely related to this one's topic. Any kind of spamming, dubious practises or removing the link will result in your link from us being dropped and, potentially, your whole site being banned.