Topotecan hydrochloride is a Topoisomerase I inhibitor. It is a semisynthetic derivative of camptothecin with antineoplastic activity. During the S phase of the cell cycle, topotecan selectively stabilizes topoisomerase I-DNA covalent complexes, inhibiting religation of topoisomerase I-mediated single-strand DNA breaks and producing potentially lethal double-strand DNA breaks when complexes are encountered by the DNA replication machinery. Camptothecin is a cytotoxic quinoline-based alkaloid extracted from the Asian tree Camptotheca acuminata.
The IC50 values of Topotecan at 24 h are 2.73±0.25 μM of U251 cells, 2.95±0.23 μM of U87 cells, 5.46±0.41 μM of GSCs-U251 and 5.95±0.24 μM of GSCs-U87.
Topotecan hydrochloride hydrate is soluble in DMSO at a concentration that is greater than or equal to 20 mg/ml.