Chelsea Therapeutics International, Ltd. has resubmitted a new drug application (NDA) to the US Food and Drug Administration (FDA) seeking approval to market Northera (droxidopa), an orally active synthetic precursor of norepinephrine, for the treatment of symptomatic neurogenic orthostatic hypotension (NOH) in patients with primary autonomic failure (Parkinson's disease, multiple system atrophy and pure autonomic failure), dopamine beta hydroxylase deficiency and non-diabetic autonomic neuropathy.

The NDA resubmission includes data from Study 306B, a large phase III study which confirms findings from Study 301 demonstrating improvement in dizziness/ lightheadedness, the cardinal symptom of NOH. Under the Prescription Drug User Fee Act, or PDUFA, the FDA is expected to review and act on the NDA six months from the date of resubmission.

"The resubmission of our Northera NDA marks a critical step in our effort to bring an important new therapeutic option to patients living with this debilitating condition," said Joseph G Oliveto, interim chief executive officer of Chelsea. "We now have two large randomized placebo-controlled clinical studies which show that treatment with Northera results in consistent and statistically significant improvements in the symptoms of NOH, and a greatly expanded database supporting the safety of Northera. We look forward to working closely with the FDA as they review our application and, in parallel, planning for commercialisation."

In addition to Study 306B, the filing also includes three smaller supportive randomized controlled trials, two long-term open-label extension studies, a dedicated thorough QTc study, a 24-hour ambulatory blood pressure monitoring study and a bioequivalence study for the 300 mg dose form of droxidopa. The bioequivalence study showed comparable pharmacokinetics between the 300 mg dose form of droxidopa and the 100 mg and 200 mg combination dose form.

As previously disclosed, FDA has indicated that the revised Northera NDA may be reviewed by the Cardiovascular and Renal Drug Advisory Committee, or CRDAC. The FDA has also raised the possibility of accelerated approval for Northera, where it has indicated that endpoints measuring short-term clinical benefits can be used as valid surrogates reasonably likely to predict long-term clinical benefits under accelerated approval. FDA also noted that the Company may be required to verify the durability of effect of Northera in a post-marketing study. Chelsea continues to work with the FDA on the design of such a study, which it intends to initiate in the fourth quarter of 2013. The study is expected to include short-term clinical endpoints should the Agency require an additional clinical trial for the approval of Northera.

Northera was previously granted Orphan Drug Designation and received Fast Track designation from the FDA. Fast Track designation is designed to facilitate the review of products that address serious or potentially life-threatening conditions for which there is an unmet medical need.

Northera (droxidopa), the lead investigational agent in Chelsea Therapeutics' pipeline, is currently in phase III development for the treatment of symptomatic neurogenic orthostatic hypotension (NOH) in patients with primary autonomic failure — an indication that includes a significant number of patients with Parkinson's disease, multiple system atrophy (MSA) and pure autonomic failure (PAF). Droxidopa is a synthetic catecholamine that is directly converted to norepinephrine (NE) via decarboxylation, resulting in increased levels of NE in the nervous system, both centrally and peripherally.

Chelsea Therapeutics is a biopharmaceutical development company that acquires and develops innovative products for the treatment of a variety of human diseases, including central nervous system disorders.