Updated from 4:45 pm ET with additional information, including CEO comments.

The FDA has approved Chelsea Therapeutics' (CHTP) Northera for the treatment of neurogenic orthostatic hypotension (NOH), a rare disease which causes a debilitating drop in blood pressure upon standing.

Here's a snippet from the FDA announcement: 

The FDA is approving Northera under the accelerated approval program, which allows for approval of a drug to treat a serious disease based on clinical data showing that the drug has an effect on an intermediate clinical measure (in this case, short-term relief of dizziness) that is reasonably likely to predict the outcome of ultimate interest (relief of dizziness during chronic treatment). This program provides patient access to promising drugs while the company conducts post-approval clinical trials to verify the drug's clinical benefit, which for this approval is a long-term effect on patient symptoms in NOH, a chronic disease.

Northera has a boxed warning to alert health care professionals and patients about the risk of increased blood pressure while lying down (supine hypertension), a common problem that affects people with primary autonomic failure and can cause stroke. It is essential that patients be reminded that they must sleep with their head and upper body elevated. Supine blood pressure should be monitored prior to and during treatment and more frequently when increasing doses.

The most common adverse events reported by clinical trial participants taking Northera were headache, dizziness, nausea, high blood pressure (hypertension) and fatigue.

The effectiveness of Northera was shown through two-weeks in two clinical trials in people with NOH. People taking Northera reported a decrease in dizziness, lightheadedness, feeling faint, or feeling as if they might black out compared to those taking an inactive pill (placebo). Durability of the improvement in patient symptoms beyond two weeks has not been demonstrated.

About that last bit. The Northera's label says the drug's efficacy "beyond 2 weeks of treatment has not yet been demonstrated, therefore the continued effectiveness of Northera in patients should be assessed periodically."

"I love the [Northera] label," said Chelsea CEO Joe Oliveto in a quick phone call. "We think it is a doctors' normal standard practice to assess the efficacy of any drug periodically."

Importantly, Chelsea avoids a worst-case scenario under which FDA might have restricted the drug's use to no more than two weeks. 

The Northera label also includes all the NOH patient populations studied and includes favorable tolerability data. The label does include a black-box warning against supine hypertension. 

Northera pricing has not yet been established. Chelsea plans to prepare for a commercial launch in the second half of the year while also exploring "strategic alternatives," Oliveto said. He has previously told investors that exploring the sale of the company is a possibility upon Northera approval, so this comment isn't new. 

Northera was approved under an accelerated approval review, which will require Chelsea to conduct a post-approval study to confirm the drug's efficacy and safety. Preliminary designs for the study call for 1,400 NOH patients to be enrolled in a study that will treat them all with Northera for three months, then randomize the patients to either continue treatment with Northera or receive a placebo. The study may take up to six years to enroll. 

Chelsea shares were halted at $4.95 prior to the Northera announcement. When trading resumed, shares rose 38% to $6.75.

Adam Feuerstein writes regularly for TheStreet. In keeping with company editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback;

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