How rimeporide works
DMD is caused by a mutation in the DMD gene, which provides instructions to build a protein called dystrophin. Dystrophin plays an essential role in the structure and function of muscle fibers, but the mutation causes no dystrophin protein to be produced.
Dystrophin is also thought to be necessary for the function of the so-called sodium/proton type 1 exchanger (NHE-1), an enzyme that functions in the cell membrane to regulate the concentration of sodium and the pH of the cells. By controlling sodium concentration, NHE-1 also indirectly influences calcium levels.
The muscle cells of DMD patients have an overload of calcium, which is thought to be caused by dysfunctional NHE-1. Over time, high calcium concentrations contribute to the muscle damage that is seen in DMD patients.
Rimeporide inhibits NHE-1, thereby correcting calcium levels in the cell.
Rimeporide in clinical trials
An open-label Phase 1b clinical trial (NCT02710591) assessed rimeporide’s safety, tolerability, and effect on muscles. A total of 20 boys, from 6 to 14 years old and with DMD, were treated with four different doses of rimeporide, ranging from 50 to 300 mg, taken by mouth three times a day for a total of four weeks.
An analysis of 15 patients showed that the medication was well-tolerated, and no serious adverse events were reported.
EspeRare is planning a Phase 2 study to further assess the efficacy of rimeporide in DMD patients.
Rimeporide was originally developed by Merck Serono to treat congestive heart failure. Trials were discontinued before Phase 2. In 2013, the company funded the launch of the EspeRare Foundation, a nonprofit organization set up by three Merck Serono employees, which obtained the rights to develop rimeporide for neuromuscular diseases.
Last updated: July 18, 2019
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