Nursing Pharmacology Chapter 33-34: Anticancer Drugs
Natural Products:
Topoisomerase Inhibitors: Camptothecins
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Camptothecins: Irinotecan and topotecan:
Camptothecin is classified as an alkaloid that was identified in plant extracts from Camptotheca acuminata , while searching for antineoplastic agents.
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There are two derivatives of camptothecin approved by the FDA for use in treating various cancers.
These agents are irinotecan (Campto) and topotecan (Hycamtin).
Review:
The enzyme DNA topoisomerases function to promote relaxation supercoil DNA torsional stress by enhancing catalysis.
The consequence of this action is sufficient to allow replication, repair as well as transcription.
We are now considering the first of two classes of topoisomerase (I and II).
These topoisomerases promote DNA strand breakage and resealing.
Camptothecin analogs limit topoisomerase I function (inhibition of the enzyme aciton).