Topotecan Description

Topotecan has the aforementioned apparatus of activity as irinotecan and is believed to apply its cytotoxic furnishings during the S-phase of DNA synthesis. Topoisomerase I relieves torsional ache in DNA by inducing capricious individual fiber breaks. Topotecan binds to the topoisomerase I-DNA circuitous and prevents religation of these individual fiber breaks.

This ternary circuitous interferes with the affective archetype fork, which leads to the consecration of archetype arrest and baleful double-stranded break in DNA. As beastly beef cannot calmly adjustment these bifold fiber breaks, the accumulation of this ternary circuitous eventually leads to apoptosis (programmed corpuscle death).

Topotecan mimics a DNA abject brace and binds at the website of DNA break by intercalating amid the upstream (−1) and after (+1) abject pairs. Intercalation displaces the after DNA, appropriately preventing religation of the broken strand. By accurately bounden to the enzyme–substrate complex, Topotecan acts as an uncompetitive inhibitor.