Niclosamide- 13 C 6 (monohydrate) is the 13 C labeled Niclosamide monohydrate. Niclosamide (BAY2353) monohydrate is an orally active antihelminthic agent used in parasitic infection research. Niclosamide monohydrate is a STAT3 inhibitor with an IC50 of 0.25 μM in HeLa cells. Niclosamide monohydrate has biological activities against cancer , and inhibits DNA replication in Vero E6 cells.