How Emflaza Works in Duchenne Muscular Dystrophy
Emflaza (deflazacort) is a corticosteroid that treats Duchenne muscular dystrophy (DMD) by reducing inflammation and slowing muscle degeneration. DMD is a genetic disorder caused by dystrophin protein deficiency, leading to muscle fiber damage, chronic inflammation, and progressive weakness. Deflazacort binds to glucocorticoid receptors in muscle cells, suppressing inflammatory cytokines like NF-κB and reducing immune cell infiltration that exacerbates muscle breakdown.[1][2]
Clinical Evidence from Trials
In the pivotal ACT DMD trial, boys aged 5-15 with DMD on deflazacort (0.9 mg/kg/day) maintained motor function longer than those on prednisone, measured by time to rise from the floor (up to 3.26 seconds better at 3 years) and 10-meter walk-run speed. It delayed milestones like loss of ambulation by about 2.5 years versus placebo standards. FDA approval in 2017 was based on this head-to-head superiority over prednisone.[1][3]
Dosing and Administration
Emflaza starts at 0.9 mg/kg/day, given orally once daily as tablets or suspension. Weight-based adjustments occur every 3 months; tapering minimizes withdrawal. It's taken with food to reduce GI upset. Long-term use requires monitoring for side effects like growth suppression or osteoporosis.[2][4]
How It Compares to Prednisone
Both are glucocorticoids, but Emflaza shows better preservation of muscle strength and stair-climbing ability with fewer weight gain issues (less cushingoid effects). Prednisone is cheaper and generic; Emflaza's branded status led to higher initial costs, sparking access debates.[1][3]
Common Side Effects and Risks
Patients report Cushing's syndrome (48%), weight gain (38%), and infections (more frequent than prednisone). Cataracts (14%) and bone fractures rise with prolonged use, prompting supplements like calcium/vitamin D and bone density scans. Growth velocity drops, but final height is often near-normal.[2][4]
When Does Treatment Start and Long-Term Outlook?
Therapy begins around age 4-5 at DMD diagnosis, before significant weakness. It doesn't cure DMD or restore dystrophin but extends ambulation by 1.5-3 years and ventilator-free breathing. Combining with exon-skipping drugs like eteplirsen is common for broader management.[1][3]
[1]: FDA Label for Emflaza
[2]: Parent Project Muscular Dystrophy - Emflaza Overview
[3]: New England Journal of Medicine - ACT DMD Trial (2017)
[4]: Drugs.com - Emflaza Side Effects