Sparsentan (RE-021; BMS-346567; PS433540; DARA-a) is a novel candidate in development by Retrophin for the treatment of focal segmental glomerulosclerosis (FSGS), a serious kidney disorder that often leads to end-stage renal disease (ESRD). Sparsentan is a single molecule with antagonism of the endothelin type A receptor (ETAR) and the angiotensin II type 1 receptor (AT1R). Sparsentan has high affinity for both the ETAR (Ki= 12.8 nM) and the AT1R (Ki=0.36 nM), and greater than 500-fold selectivity for these receptors over the endothelin type B and angiotensin II subtype 2 receptors. Endothelin-1 and angiotensin II are thought to contribute to the pathogenesis of IgAN via the ETAR and AT1R, respectively. The US Food and Drug Administration gave accelerated approval on February 17 2023 to sparsentan (Filspari), the first non-immunosuppressive therapy labeled for treating adults with primary immunoglobulin A (IgA) nephropathy.

Propagermanium, a newly introduced hydrophilic polymer of 3-oxygermanium propionic acid (3,3’-(1,3- dioxo-1,3-digermoxanediyl) bispropionic acid) has been reported to have antiinflammatory, antiviral and antineoplastic properties. In Japan propagermanium is approved for the treatment of HBe positive chronic hepatitis B. A postmarketing survey, however, revealed the occurrence of moderate to severe liver damage after the treatment in about 4% of patients. In most countries propagermanium falls under the regulations of dietary supplements. An import alert on germanium products was imposed by the U.S. FDA in 1988, because of possible injury to health. In Germany governmental institutions warned consumers of possibly fatal kidney damage.