INT131

INT131 is a non-thiazolidinedione, selective modulator of the peroxisome proliferator-activated receptor gamma (PPAR-gamma), a nuclear receptor that governs insulin sensitivity, fat-cell development and glucose handling. It was created by InteKrin Therapeutics as a second-generation insulin sensitizer, following the first-generation PPAR-gamma full agonists (the thiazolidinediones, or TZDs, such as rosiglitazone and pioglitazone). The compound, a besylate salt in its clinical form, was engineered using preclinical models to bind PPAR-gamma with high affinity but to activate it only partially, so as to separate the drug's antidiabetic action from the effects on fat tissue and fluid balance that limit the older drugs ^[1][4].

In laboratory and animal studies INT131 lowered glucose and improved insulin sensitivity comparably to full PPAR-gamma agonists, but with much less of the adipogenesis (fat-cell formation) and fluid retention that mark the TZDs ^[1][4]. In insulin-resistant obese mice it restored defective insulin signaling in muscle and fat and, notably, increased bone mineral density rather than reducing it, addressing a known drawback of the TZD class ^[2]. The pivotal human evidence came from a randomized Phase 2 trial in people with type 2 diabetes that compared INT131 against both placebo and pioglitazone, in which INT131 produced dose-dependent reductions in hemoglobin A1c that reached efficacy on a par with pioglitazone, yet with less edema, weight gain and hemodilution, consistent with its selective-modulator design ^[3].

INT131 illustrated the selective PPAR-gamma modulator concept, an attempt to build a safer insulin sensitizer by tuning how strongly the receptor is switched on. Despite encouraging Phase 2 results, it did not advance to approval, and development did not carry it to market; it remains an investigational compound rather than a prescribable medicine, and it is discussed largely in the context of diabetes drug research and the broader effort to improve on the thiazolidinediones ^[1][4]. It is not available as a supplement or approved therapy.

Investigational, not approved. The whole design goal is fewer of the glitazone problems (edema, weight gain, heart-failure risk in susceptible people, bone loss), and trials suggested a milder profile, but the class-level cautions still apply and long-term human data is limited. Research use only.