Pyrimethamine is a potent inhibitor of multi-drug and toxin extrusion transporters. This compound inhibits Mdr-1(P-glycoprotein) and thus allows for active drugs to stay within the cell for longer periods of time, increasing their effectiveness by preventing efflux of the active compound from the cytoplasm. Pyrimethamine also inhibits DHFR(dihydrofolate reductase ).
Loutfy, M.A., et al.: Anal. Profiles Drug Subs., 12, 463 (1983), Leport, C., et al.: Am. J. Med., 84, 94 (1988), McIntosh, H.M., et al.: Ann. Trop. Med., Parasitol., 93, 265 (1998), Plowe, C.V., et al.: Br. Med. J., 328, 545 (2004),