Northera, the Chelsea Therapeutics (NASDAQ:CHTP) compound developed to treat dizziness and fainting in Parkinson’s disease patients, could get word from regulators today on marketing approval.

The Prescription Drug User Fee Act (PDUFA) action date was set when the U.S. Food and Drug Administration granted priority review for the compound. Northera passed a hurdle last month when an independent advisory panel to the U.S. Food and Drug Administration voted 7-4 to recommend FDA approval. The recommendation is not binding but it is considered when the FDA deliberates whether to approve a new drug.

Northera was developed to treat neurogenic orthostatic hypotension, or NOH. The disorder is characterized by a sudden drop in blood pressure that leads to dizziness and fainting. Northera would be used to treat NOH in Parkinson’s patients as well as in patients who have multiple systems atrophy and pure autonomic failure. Chelsea licensed the compound, also called droxidopa, from Japanese drug company Sumitomo Pharma. Droxidopa has been used in Japan since 1989 and generates about $50 million in annual sales. But NOH is rare. In documents filed with the FDA, Chelsea said that the number of U.S. patients who have NOH is estimated at just 80,000

Northera would become Charlotte-based Chelsea’s first approved drug.

The company has said that while it plans to commercialize Northera in the United States, it would seek licensing deals with pharmaceutical partners to bring the drug to markets around the world. First, Northera needs to secure FDA approval. Here’s how the decision could play out.

The case for Northera FDA approval.

There is a reason that the FDA granted Northera orphan drug status and then later, priority review. Patients who have NOH don’t have a lot of treatment options right now. Shire’s (NASDAQ:SHPGY) ProAmatine is the only FDA-approved NOH treatment but that drug carries a black box warning due to safety risks. Late last year, Shire reached an agreement with the FDA to conduct two new clinical trials on the drug by the end of 2014 to show its benefit. If the new trials don’t show benefit ProAmatine’s marketing approval could be withdrawn. Even if ProAmatine demonstrates benefit, Northera would give NOH patients another choice.

The FDA advisory committee did raise questions about Northera’s benefit, the duration of the drug’s benefit and the fact that not all patients in clinical trials showed benefit. But some patients did show benefit from Northera and given the scarcity of NOH treatments, that benefit weighs in the drug’s favor. If ProAmatine loses marketing approval Northera could become the only FDA-approved choice for patients who have NOH.

The case for a Northera rejection.

The 7-4 advisory committee is a little shakier than that vote total suggests. Not included in that tally is one abstention and one non- vote. That means nearly half of the panel was not sufficiently convinced that Northera demonstrated sufficient safety and efficacy. Northera had only one successful clinical trial and the FDA might also conclude that the compound’s benefit is insufficient. The FDA may also be concerned that Northera’s benefit is outweighed by safety risks. The FDA reviewer’s report noted that at least 19 deaths were reported in clinical trials. Chelsea said the deaths were not attributed to the treatment. The company also points to a 10-year study in Japan conducted after droxidopa reached the market. But the FDA review said it’s difficult to interpret data from an uncontrolled study of patients. If the FDA remains insufficiently convinced about Northera, expect a delay rather than an outright rejection. A complete response letter will outline what additional information the agency needs to see in order for the Northera to receive approval. That would require Chelsea to conduct more clinical testing.