Carbidopa ((S)-(-)-Carbidopa) monohydrate exhibits activities similar to that described for other AhR ligands in BχPC3 and Capan-2 cells, namely the induction of CYP1A1 and CYP1A2, which are inhibited by AhR antagonists such as CH223191.
Carbidopa, a aromatic-L-amino acid decarboxylase inhibitor, is selectively cytotoxic to human pulmonary carcinoid and small cell lung carcinoma cells. Carbidopa is lethal (IC ₅₀ =29 μM).

Carbidopa monohydrate also induces nuclear uptake of the AhR, and in vivo studies show that carbidopa at a dose of 1 mg/mouse significantly inhibits tumor growth in athymic nude mice bearing BχPC3 cells as xenografts.