Drotaverine - a Concealed Cytostatic!

Drotaverine (also known as dihydroperparine or No-Spa® ) is an antispasmodic drug closely related to papaverin. Drotaverin also acts as a cytostatic compound for several human tumor cell lines and nonmalignant mouse fibroblasts, and EC50 values as low as 3.0 μM were observed in SRB assays for HT-29 human colorectal carcinoma cells. Small structural changes (e.g., aromatization, benzylic oxidation) led to a reduced activity or a complete loss of cytotoxicity. Staining of the cells with acridine orange showed the cell membrane of the dead cells to be still intact, and a slight G1/G0 arrest in the treated cells was observed after 24 h. Extra annexin V-FITC/PI assays and flow cytometry revealed drotaverine mainly to act as a cytostatic and only to a minor extent as cytotoxic agent.