Experimental drug aids skeletal and heart muscles for DMD

A drug for Duchenne muscular dystrophy (DMD) called Vamorolone, has been tested for giving the benefits of two already established therapies called Prednisone and Eplerenone. The new drug in question provides less side effects as an animal study has concluded.

DMD is the most common type of muscular dystrophy, it is caused by changes in the DMD gene that gives commands for the making of the dystrophin protein. Dystrophin works together with other proteins to reinforce muscle fibres and guard them from harm as muscles contract and relax.

Prednisone, is a strong anti-inflammatory medicine and considered the golden standard for treating DMD. Although Prednisone its long-term use is associated with severe side effects, including bone fragility, stunted growth, weight gain, behaviour issues, cataracts, and adrenal suppression.

Tests results showed that aldosterone treatment and MR activation led to a substantial increase in kidney size and high blood pressure in both healthy and DMD mice.

MR activation triggered by aldosterone also increased the size of the heart and caused tissue fibrosis (scarring) in DMD animals, which were mitigated by all MR antagonists.

Christopher Heier, PhD, assistant professor at Children’s National Health System said: “Some drugs can interact with both the mineralocorticoid receptor (MR) and glucocorticoid receptor (GR) since these two drug targets evolved from a common ancestor.

“The experimental drug Vamorolone safely targets both the GR to treat chronic inflammation and the MR to treat the heart. However, we find these two drug targets can play distinctly different roles in heart and skeletal muscle,”

Regarding safety, researchers reported that daily Prednisone therapy was associated with side effects, including hyperinsulinemia (unwarranted levels of insulin in the blood), while Vamorolone aided heart function without associated side effects.

Heier added: “These findings have the potential to help current and future patients. Clinicians already prescribe several of these drugs. Our new data support the use of MR antagonists such as Eplerenone in protecting DMD hearts, particularly if patients take prednisone”.