Fanotaprim is a dihydrofolate reductase (DHFR) inhibitor, suppressing the growth of T. gondii strains with a TgDHFR IC50 of 1.57 ± 0.11 nM, a hDHFR IC50 of 308 ± 71 nM, and a hDHFR to TgDHFR selectivity ratio of 196.

TgDHFR:1.57 ± 0.11 nM(Toxoplasma gondii), DHFR (human):308 ± 71 nM(human)

Fanotaprim exhibits parasiticidal and antiproliferative effects with EC50s of 13 and 7300 nM against the type I RH strain of T. gondii and MCF-7 cells, respectively[1]. It also inhibits the growth of T. gondii strains in vitro with EC50s ranging from 7.6 to 29.8 nM (GT1, ME49, CTG, RUB, and VAND)[1].

Fanotaprim (1-10 mg/kg; p.o.; daily; beginning on day 1 through day 7) is highly effective in controlling acute infection by highly virulent strains of T. gondii in the murine model[1]. In mice, Fanotaprim (1 mg/kg; i.v.) shows CL, Vd, and t1/2 values of 10.6 mL/min/kg, 1.14 L/kg, and 3.9 hours, respectively[1]. When administered orally at 0.83 mg/kg, Fanotaprim exhibits F, Cmax, Tmax, and AUC0-last values of 47.3%, 178 ng/mL, 0.05 hours, and 750 ng h/mL, respectively[1].