Exondys 51
(Eteplirsen)Dosage & Administration
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Exondys 51 Prescribing Information
Dosage and Administration (EXONDYS 51 is supplied in single-dose vials as a preservative-free concentrated solution that requires dilution prior to administration. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. Use aseptic technique.
| 08/2025 |
EXONDYS 51 is indicated for the treatment of Duchenne muscular dystrophy (DMD) in patients who have a confirmed mutation of the DMD gene that is amenable to exon 51 skipping. This indication is approved under accelerated approval based on an increase in dystrophin in skeletal muscle observed in some patients treated with EXONDYS 51
EXONDYS 51 was evaluated in three clinical studies in patients who have a confirmed mutation of the DMD gene that is amenable to exon 51 skipping.
In Study 1, patients were randomized to receive weekly infusions of EXONDYS 51 (30 mg/kg, n=4); EXONDYS 51 (50 mg/kg, n=4), or placebo (n=4) for 24 weeks. The primary endpoint was dystrophin production; a clinical outcome measure, the 6-minute walk test (6MWT), was also assessed. The 6MWT measures the distance that a patient can walk on a flat, hard surface in a period of 6 minutes. Patients had a mean age of 9.4 years, a mean 6-minute walk distance (6MWD) at baseline of 363 meters, and were on a stable dose of corticosteroids for at least 6 months. There was no significant difference in change in 6MWD between patients treated with EXONDYS 51 and those treated with placebo.
All 12 patients who participated in Study 1 continued treatment with open-label EXONDYS 51 weekly for an additional 4 years in Study 2. The 4 patients who had been randomized to placebo were re-randomized 1:1 to EXONDYS 51 30 or 50 mg/kg/week such that there were 6 patients on each dose. Patients who participated in Study 2 were compared to an external control group. The primary clinical efficacy outcome measure was the 6MWT. Eleven patients in Study 2 had a muscle biopsy after 180 weeks of treatment with EXONDYS 51, which was analyzed for dystrophin protein level by Sarepta western blot. Study 2 failed to provide evidence of a clinical benefit of EXONDYS 51 compared to the external control group. The average dystrophin protein level after 180 weeks of treatment with EXONDYS 51 was 0.93% of the dystrophin level in healthy subjects. Because of insufficient information on dystrophin protein levels before treatment with EXONDYS 51 in Study 1, it is not possible to estimate dystrophin production in response to EXONDYS 51 in Study 1.
In Study 3, 13 patients were treated with open-label EXONDYS 51 (30 mg/kg) weekly for 48 weeks and had a muscle biopsy at baseline and after 48 weeks of treatment. Patients had a mean age of 8.9 years and were on a stable dose of corticosteroids for at least 6 months. Dystrophin levels in muscle tissue were assessed by Western blot. In the 12 patients with evaluable results, the pre-treatment dystrophin level was 0.16% ± 0.12% (mean ± standard deviation) of the dystrophin level in a healthy subject and 0.44% ± 0.43% after 48 weeks of treatment with EXONDYS 51 (
Individual patient dystrophin levels from Study 3 are shown in Table 2.
| Patient Number | Baseline % normal dystrophin | Week 48 % normal dystrophin | Change from Baseline % normal dystrophin |
| 1 | 0.13 | 0.26 | 0.13 |
| 2 | 0.35 | 0.36 | 0.01 |
| 3 | 0.06 | 0.37 | 0.31 |
| 4 | 0.04 | 0.10 | 0.06 |
| 5 | 0.17 | 1.02 | 0.85 |
| 6 | 0.37 | 0.30 | -0.07 |
| 7 | 0.17 | 0.42 | 0.25 |
| 8 | 0.24 | 1.57 | 1.33 |
| 9 | 0.11 | 0.12 | 0.01 |
| 10 | 0.05 | 0.47 | 0.43 |
| 11 | 0.02 | 0.09 | 0.07 |
| 12 | 0.18 | 0.21 | 0.03 |
| Mean | 0.16 | 0.44 | 0.28; p =0.008 |
- 30 milligrams per kilogram of body weight once weekly ()
2.1 Dosing InformationThe recommended dose of EXONDYS 51 is 30 milligrams per kilogram administered once weekly as a 35 to 60 minute intravenous infusion via an in-line 0.2 micron filter.
If a dose of EXONDYS 51 is missed, it may be administered as soon as possible after the scheduled time.
- Administer as an intravenous infusion over 35 to 60 minutes via an in-line 0.2 micron filter (,
2.1 Dosing InformationThe recommended dose of EXONDYS 51 is 30 milligrams per kilogram administered once weekly as a 35 to 60 minute intravenous infusion via an in-line 0.2 micron filter.
If a dose of EXONDYS 51 is missed, it may be administered as soon as possible after the scheduled time.
)2.3 Administration InstructionsApplication of a topical anesthetic cream to the infusion site prior to administration of EXONDYS 51 may be considered.
EXONDYS 51 is administered via intravenous infusion. Flush the intravenous access line with 0.9% Sodium Chloride Injection, USP, prior to and after infusion.
Infuse the diluted EXONDYS 51 solution over 35 to 60 minutes via an in-line 0.2 micron filter. Do not mix other medications with EXONDYS 51 or infuse other medications concomitantly via the same intravenous access line.
If a hypersensitivity reaction occurs, consider slowing the infusion or interrupting the EXONDYS 51 therapy
[see Warnings and Precautions and Adverse Reactions ]. - Dilution required prior to administration ()
2.2 Preparation InstructionsEXONDYS 51 is supplied in single-dose vials as a preservative-free concentrated solution that requires dilution prior to administration. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. Use aseptic technique.
- Calculate the total dose of EXONDYS 51 to be administered based on the patient's weight and the recommended dose of 30 milligrams per kilogram. Determine the volume of EXONDYS 51 needed and the correct number of vials to supply the full calculated dose.
- Allow vials to warm to room temperature. Mix the contents of each vial by gently inverting 2 or 3 times. Do not shake.
- Visually inspect each vial of EXONDYS 51. EXONDYS 51 is a clear, colorless solution that may have some opalescence, and may contain white to off-white amorphous particles. Do not use if the solution in the vials is cloudy, discolored or contains extraneous particulate matter other than white to off-white amorphous particles.
- With a syringe fitted with a 21-gauge or smaller non-coring needle, withdraw the calculated volume of EXONDYS 51 from the appropriate number of vials.
- Dilute the withdrawn EXONDYS 51 in 0.9% Sodium Chloride Injection, USP, to make a total volume of 100-150 mL. Visually inspect the diluted solution. Do not use if the solution is cloudy, discolored or contains extraneous particulate matter other than white to off-white amorphous particles.
- Administer the diluted solution via an in-line 0.2 micron filter.
- EXONDYS 51 contains no preservatives and should be administered immediately after dilution. Complete infusion of diluted EXONDYS 51 solution within 8 hours of dilution. If immediate use is not possible, the diluted solution may be stored for up to 24 hours at 2ºC to 8ºC (36ºF to 46ºF). Do not freeze. Discard unused EXONDYS 51.
EXONDYS 51 is a clear and colorless solution that may have some opalescence, and may contain white to off-white amorphous particles, and is available as follows:
- Injection: 100 mg/2 mL (50 mg/mL) solution in a single-dose vial
- Injection: 500 mg/10 mL (50 mg/mL) solution in a single-dose vial
There are no human or animal data available to assess the use of EXONDYS 51 during pregnancy. In the U.S. general population, major birth defects occur in 2 to 4% and miscarriage occurs in 15 to 20% of clinically recognized pregnancies.
None.