A New Drug Application (NDA) has been submitted to the Food and Drug Administration for intranasal dihydroergotamine mesylate (INP104; Impel NeuroPharma) to treat acute migraine.

INP104 uses proprietary technology to deliver a lower dose (1.45mg) of dihydroergotamine mesylate (DHE) to the upper nasal space. The Company believes this formulation may potentially reduce treatment emergent adverse events. An intranasal formulation of DHE that delivers a higher dose is currently approved by the FDA under the brand name Migranal (4mg/mL). 

The NDA submission is supported by data from the phase 3 STOP-301 study that included 354 patients who had a documented diagnosis of migraine with or without aura, with at least 2 attacks per month for the previous 6 months. Patients who received at least 1 dose of INP104 comprised the Full Safety Set (n=354), and patients who took at least 2 doses of INP104 per 28-day period during the 24-week treatment period comprised the Primary Safety Set (n=185). The primary safety end points included serious and non-serious treatment emergent adverse events as well as changes in nasal mucosa and olfactory function. 

Results showed the study met its primary end points with no new safety signals. Most of the treatment emergent adverse events in the Full Safety Set were mild and transient in nature with no serious adverse events reported. The most common adverse events (≥5%) were nasal congestion (16.7%), nausea (7.9%), nasal discomfort (5.4%) and abnormal taste (5.1%).

Additionally, exploratory efficacy data in the Full Safety Set showed that after the first dose, 66.3% of patients achieved pain relief, 38% of patients had pain freedom, and 52% had freedom from their most bothersome migraine symptom (MBS) at 2 hours; 33.1% of patients in the Primary Safety Set achieved pain freedom at 2 hours. Initial pain relief as early as 15 minutes was reported in 16.3% of patients with continued improvement over time. The study also showed that a majority of migraine attacks did not require rescue medication (85%).

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“Based upon the previously reported positive results of the STOP 301 study, we believe that INP104 has the potential to provide an important new option for people who need a fast, effective, and consistently reliable acute treatment of migraine headaches,” said Adrian Adams, chairman and CEO of Impel NeuroPharma.

For more information visit impelnp.com.


  1. Impel NeuroPharma announces FDA submission of New Drug Application for INP104 for the acute treatment of migraine. [press release]. Seattle, WA: Impel NeuroPharma; November 9, 2020. 
  2. Impel NeuroPharma announces primary objectives met in pivotal phase 3 registration study of INP104 for the treatment of acute migraine. [press release]. Seattle, WA: Impel NeuroPharma; June 10, 2020.