Health Organization for Pudendal Education

Two drugs, losartan and pirfenidone, have shown promise in reducing fibrosis (scar formation) in mice that lack the muscle protein dystrophin and have a disease resembling Duchenne muscular dystrophy (DMD).

Both drugs target the natural body compound transforming growth factor beta (TGF-beta), which interferes with muscle fiber formation and promotes formation of scar tissue (fibrosis) in response to injury, inflammation or disease.

Fibrosis, the result of excess deposition of connective tissue, is a major factor in muscle function impairment in human DMD.

Luc Gosselin, an MDA research grantee at the State University of New York at Buffalo, and colleagues, who published results of their work with pirfenidone in the February issue of Muscle & Nerve, found the drug was somewhat effective in reducing fibrosis in mice treated for four weeks, but they say more testing at higher doses is needed.

Pirfenidone is in development by InterMune of Brisbane, Calif., for the treatment of interstitial pulmonary fibrosis, a condition in which excess collagen interferes with lung function.

In a separate study, Ronald Cohn at Johns Hopkins University in Baltimore and colleagues, who published their findings online Jan. 21 in Nature Medicine, had more success with another antifibrosis drug, losartan, which they tested in dystrophin-deficient, DMD-affected mice for 6 to 9 months.

In the losartan-treated mice, the diaphragm muscles showed less scarring (fibrosis in 18 percent of the tissue, compared to 32 percent in untreated mice). The mice had significantly better front and back leg grip strength than did their untreated counterparts, showed less muscle fatigue when challenged, and had muscle fibers that looked more normal.