WikiMD


W8MD Diet | COVID-19 portal | Vitamin D | Vaccine | Keto

WikiMD is the world's largest medical encyclopedia with
29,044 pages, 4,107,633 edits & 35,806,679 views.

Free unbiased diet, health and wellness info!

Topoisomerase Inhibitors

From WikiMD's free health, diet & wellness encyclopedia
Jump to navigation Jump to search

Information about Topoisomerase Inhibitors

Topoisomerase I and II are normal host enzymes that are found in the nucleus of mammalian cells and are required for normal DNA replication and cellular division.  The enzymes create and then repair single stranded nicks in cellular DNA.  The nicks allow for the untangling and relaxation of supercoiled double stranded DNA, so that replication can proceed.  Once the DNA torsional strain has been relieved, the topoisomerase reseals the relaxed double helix.  Topoisomerase activity is particularly increased in rapidly dividing and in cancer cells.  It represents an appropriate, but nonselective target for anticancer therapy.

Mechanism of action of Topoisomerase Inhibitors

Topoisomerase inhibitors in current use in the United States include irinotecan and topotecan, inhibitors of topoisomerase I, and etoposide and teniposide, inhibitors of topoisomerase II.  All four agents are semisynthetic analogues of natural toxins that were initially identified in plants.  All four are given parenterally, typically in combination with other antineoplastic agents in cycles of every 3 to 4 weeks.  The major dose limiting toxicities of topoisomerase inhibitors are largely hematologic (neutropenia, anemia, thrombocytopenia) and gastrointestinal (diarrhea, nausea).  While serum enzyme elevations are not uncommon with chemotherapeutic regimens that include topoisomerase inhibitors, clinically apparent liver injury is uncommon.

Irinotecan and topotecan are derived from camptothecins, cytotoxic compounds which were initially isolated from the bark of the Chinese tree, Camptotheca acuminata.  These agents bind to the DNA-topoisomerase I complex and prevent resealing of the DNA.  Accumulation of DNA breaks results in inhibition of DNA replication and cell death.  Once the mechanism of toxicity of camptothecins was elucidated, more soluble and less toxic analogues were produced.  Irinotecan and topotecan are two camptothecin derivatives currently in use in the United States and are used as adjunctive therapies for advanced colorectal, ovarian and small cell lung cancer. Etoposide and teniposide are semisynthetic derivatives of extracts of the American mandrake plant or Mayapple (Podophyllum peltatum) and bind to topoisomerase II and DNA, preventing the resealing of DNA breaks and thus causing inhibition of DNA replication and cell death.  These agents are in current use as adjunctive therapies for advanced testicular and small cell lung cancer (etoposide, originally called VP-16), and for acute leukemia in children and malignant brain tumors (teniposide, VP-26).

Drug class for Topoisomerase Inhibitors

Drug Class:antineoplastic agents Drugs in the Subclass Topoisomerase Inhibitors:EtoposideIrinotecanTeniposideT opotecan

Alphabetic list of antineoplastic agents - 0-9 - A1 - A2 - A3 - A4 - A5 -A6 - B - C - D - E - F - G - H - I - JK - L - M - NO - PQ - R - S - T - UVW - XYZ

Cost and Coupons - Topoisomerase Inhibitors

Reviews for Topoisomerase Inhibitors

Learn more about Topoisomerase Inhibitors

Latest research (Pubmed)

PubMed
Wikipedia

External links


edit 

WikiMD needs you!

This WikiMD article Topoisomerase Inhibitors is a stub.
If you are a healthcare professional familiar with the topic Topoisomerase Inhibitors, or
A subject matter expert or authority on Topoisomerase Inhibitors, you can help us.
About | Mission | Paid editors welcome!

Topoisomerase Inhibitors is part of WikiMD's Physician reviewed^ articles available 4free, 4all, 4ever!
Medicine: Health - Encyclopedia‏‎‏‎ - Topics‏‎ -‏‎ Diseases‏‎ - Cancer - Rare diseases - Random Page Navigation: Drugs - Wellness - Obesity‏‎ - Diet - Ketogenic diet - W8MD weight loss diet - Editors: Recently Edited Pages - Alphabetical Order - Sponsors - USMLE The content on or accessible through WikiMD is for informational purposes only. WikiMD is not a substitute for professional medical advice. ^See full Disclaimers
W8MD weight loss logo

Ad. Tired of being overweight?. W8MD's physician weight loss program can HELP*
Special: W8MD's tele-weight loss consultations only $99.99. Call 718-946-5500. Limited acceptance.