The high-affinity pentamidine transporter (HAPT1) is inhibited by Propamidine but displays only low affinity to Stilbamidine dihydrochloride. adenosine-sensitive pentamidine transporter (ASPT1), in contrast, is strongly inhibited by Stilbamidine dihydrochloride, and Propamidine. [3H]pentamidine uptake is determined in the presence of various concentrations of adenosine (IC50=1.2 μM) or melarsen oxide (IC50=0.7 μM), as well as in the presence of 250 μM adenosine and increasing concentrations of hypoxanthine, Propamidine (IC50=6.1 μM) and Stilbamidine dihydrochloride (IC50=110 μM)[1]. The two diamidine compounds, Stilbamidine dihydrochloride and Pentamidine are used to treat in multiple myeloma, a disease in which increase of the globulin content of the serum is of frequent occurrence[2].
References:
[1]. De Koning HP. Uptake of pentamidine in Trypanosoma brucei brucei is mediated by three distinct transporters: implications for cross-resistance with arsenicals. Mol Pharmacol. 2001 Mar;59(3):586-92.
[2]. BREWER AE.et al. Multiple myeloma treated with stilbamidine and pentamidine. Br Med J. 1948 Dec 4;2(4587):978-82.