Quinidine (Chinidin, Pitayine, β-quinine, (+)-quinidine) acts as a blocker of voltage-gated sodium channels, also an antimuscarinic and antimalarial.
Quinidine selectively reduces the proliferation of merlin-deficient HMM cell lines by causing a G0/G1 arrest, whereas the proliferation rates of merlinexpressing HMM cell lines remain unchanged. In addtion to its function as a channel blocker, quinidine is an inhibitor of a specific isoform of the cytochrome P450 family (CYP2D6), which is involved in the detoxification and metabolism of multiple commonly prescribed drugs as well as numerous endogenous substrates[1].
Quinidine is a potent and selective inhibitor of P450db and that quinidine can inhibit the in vivo metabolism of debrisoquine in humans. Quinidine is an inhibitor of amphetamine metabolism in vivo[2].
[1] Tsuruo T, et al. Cancer Res. 1984, 44(10):4303-7. [2] David E Moody, et al. Journal of Analytical Toxicology. 1990, 14: 311-317.