Shares in Chelsea Therapeutics (CHTP) skyrocketed Wednesday after the FDA surprised some market watchers by approving the company’s lead drug candidate, Northera, for treatment of neurogenic orthostatic hypotension (NOH), a rare form of low blood pressure that affects with certain neurological disorders including Parkinson’s Disease.

The stock climbed 91.74 percent on Wednesday after the FDA announced its decision after market close on Wednesday.

Northera Approval Drives Spike

The FDA panel voted 16-1 in favor of approving Northera. The overwhelming victory for Chelsea surprised some given the relative lack of clinical data available. However, the lack of alternatives for the rare condition appears to have driven the FDA to overlook the treatment’s shortcomings as a candidate.

University of Texas Southwest Medical Center cardiologist Dr. James de Lemos stated that his vote for approval was "based on the compelling evidence of suffering and the absence of viable alternatives…"

However, the panel did note that further study appeared necessary. The clinical data was seen as being incomplete, relying on testimonials from patient advocates that didn’t appear to be backed up with clinical results.

What’s more, while the benefits after one week were clearly demonstrated in trials, the long-term benefits remain less clear. Most panelists stipulated that their approval came with the understanding that further study regarding the long-term benefits was necessary. The FDA had previously reversed a narrow vote to approve Northera in early 2012 based on a lack of evidence regarding the drug's long-term effects.

Wild Price Swings for Chelsea in 2014, 2013

Jan. 14 has long been circled on the calendar for any close follower of Chelsea’s stock. The company gained over 450 percent last year on speculation that Northera would be approved. However, Wednesday’s big gains were set up by a 50 percent drop in value since the start of 2014.

The sharp downturn this year was driven by widespread speculation that the FDA panel would not approve Northera. The FDA’s Melanie Blank released a harsh medical review on Jan. 10 that featured seven reasons arguing against approval and just five in favor.

“The primary reason to not recommend approval is the lack of sufficient evidence of efficacy,” Blank wrote. “There is only one successful trial and it is well known that random factors can cause erroneous clinical trial outcomes. Patients with symptomatic neurogenic orthostatic hypotension are vulnerable and it is important to ensure their safety by protecting them from exposure to drugs that may not be effective, particularly drugs that have a theoretical basis for causing cardiovascular safety issues, as this drug has. Additionally, the lack of evidence of durability is particularly concerning. Patients should not be exposed to a drug chronically unless benefit is established over a reasonable amount of time – at least three months.”

Shares plunged nearly 30 percent on Friday as a result, but today’s approval now has investors looking at Blank’s harsh review in the rearview mirror.