Ertiprotafib is a PTP1B, IkB kinase β (IKK-β), and a dual PPARα and PPARβ agonist inhibitor ( IC50s: 1.6 μM for PTP1B, 400 nM for IKK-β, an EC50 of ~1 μM for PPARα/PPARβ).

Ertiprotafib is a potent IKK-β inhibitor (IC50: 400 nM), which is much lower than that required for the half-maximal inhibition of the p-nitrophenyl phosphatase activity of PTP1B. Ertiprotafib is at least a dual PPARα and PPARβ agonist with EC50 values for transactivation of 1 μM. The reported IC50 value of Ertiprotafib against PTP1B ranges from 1.6 to 29 μM depending on the assay conditions [2]. Such activities readily explain the observations with suprapharmacologic doses of these [1].

As seen with the treatment of ob/ob mice, both Ertiprotafib and compound 3 seem to obviously improve glucose metabolism in rats. Both Ertiprotafib and compound 3 increase in glucose disposal after an oral challenge. It is noteworthy that lipid levels are also reduced in treated animals. At 25 mg/kg/day, these compounds reduce both fasting blood glucose and insulin levels compared with vehicle-treated rats. Both triglyceride and free fatty acid levels are substantially reduced in rats treated with 25 mg/kg/day of either compound. Decreased lipid levels may be unexpected for a pure PTP1b inhibitor. As mentioned above, that rats treated with suprapharmacologic doses of Ertiprotafib display signs of PPAR family activation [2].