Emflaza (Deflazacort)

Last updated Feb. 24, 2022, by Teresa Carvalho, MS

✅ Fact-checked by José Lopes, PhD

Emflaza (deflazacort) is a corticosteroid used to treat Duchenne muscular dystrophy (DMD) in patients ages 2 and older.

Marketed by PTC Therapeutics, it was approved by the U.S. Food and Drug Administration (FDA) in 2017 as the first corticosteroid therapy to treat patients ages 5 and older regardless of disease-causing genetic mutation.

It was authorized for patients as young as 2 in 2019.

How Emflaza works

DMD is a type of muscular dystrophy, a group of diseases characterized by muscle weakness and wasting. It’s caused by mutations in the gene that codes for dystrophin, an important structural protein that provides support for muscle cells as they stretch and contract with motion. These mutations lead to a lack of dystrophin, which causes progressive muscle damage and loss.

One factor that contributes to DMD disease progression is inflammation. While inflammation normally triggers healing processes in the body, chronic immune system activation promotes muscle cells to break down, which can accelerate disease progression.

Emflaza is a corticosteroid pro-drug, meaning it must be metabolized in the body into its active form. Once metabolized, Emflaza’s active metabolite, 21-desDFZ, acts through the glucocorticoid receptor to exert anti-inflammatory effects and suppress the immune system.

Emflaza in clinical trials

Emflaza was approved based on the results of a Phase 3, double-blind clinical trial in the U.S. and Canada. This one-year study included 196 boys with DMD, ages 5 to 15.

In the first part of the trial, patients were randomly assigned to receive either Emflaza (0.9 or 1.2 mg per kg of body weight each day), a comparable corticosteroid (prednisone), or a placebo for 12 weeks, or about three months. In the second part, patients who took a placebo received either Emflaza or prednisone for 40 weeks, or about 10 months. Those already on Emflaza or prednisone continued on it. One of the measures assessed in the trial was average muscle strength.

The trial showed that both therapies significantly improved muscle strength at about three months, compared with a placebo, but only the lower dose of Emflaza led to significant muscle strength improvement up to week 52 (the one-year mark) compared with the prednisone group. Also, weight and body mass index (a measure of body fat) gains were lower with Emflaza than with prednisone throughout the trial.

Though not statistically significant, tests of participants’ function — measuring the time it took to stand from a supine position, to climb four stairs, and to walk or run 30 feet — also showed improvements with Emflaza compared with prednisone from weeks 12 to 52.

Data from a two-year, double-blind trial involving 29 patients in Italy also were considered. Boys ages 6 to 12 were randomly assigned to receive Emflaza or a placebo.

The study assessed the change in average muscle strength up to two years or loss of ambulation. Results showed a higher average muscle strength among boys treated with Emflaza compared with those on a placebo. The study found that treated patients appeared to keep the ability to walk for a longer period than those in the placebo group.

Other information

Emflaza is an oral treatment available in tablets of 6, 18, 30, and 36 mg, and as a solution at 22.75 mg/mL.

The recommended daily dosage is 0.9 mg/kg/day, which should be discontinued gradually when taken for more than a few days.

Emflaza is contraindicated in, and should not be given to people who have had allergic reactions to deflazacort or any of the components of the therapy. The treatment should be stopped if serious skin rashes occur.

Common side effects include facial puffiness, weight gain, increased appetite, upper respiratory tract infections, coughing, frequent daytime urination, unwanted hair growth, and obesity.

The treatment may alter endocrine (hormone-related) function and lead to Cushing’s syndrome and increased blood sugar levels. Patients also may be at increased risk of infections and gastrointestinal problems, whose symptoms may be masked.

It also may cause behavioral problems, including euphoria, insomnia, mood changes, depression, and psychosis. Patients on chronic Emflaza treatment should be monitored for bone mineral density. Eye problems, such as cataracts (clouding of the eye lens) and glaucoma (damage to the optic nerve, often due to high pressure in the eye) also may occur.

Because Emflaza suppresses the immune system, patients are recommended to be vaccinated with live or live-attenuated vaccines at least four to six weeks before starting Emflaza therapy.

Those taking moderate or strong CYP3A4 inhibitors (such as erythromycin, an antibiotic) should be given one-third of the recommended Emflaza dosage. Those taking moderate or strong CYP3A4 inducers (which include phenobarbital, an anticonvulsant) should not take Emflaza as its effectiveness may be reduced.

More information may be found on Emflaza’s label.


Muscular Dystrophy News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.

Forums CTA