Discovery Laboratories Inc. (DSCO) said Wednesday the Food and Drug Administration would apply a new standard in determining respiratory drug Surfaxin’s comparability to commercial product before approval.

Surfaxin, aimed at treating respiratory distress syndrome in infants has wended through the FDA's approval process for more than four years.

The biotechnology company said in a June 2 meeting the FDA reversed course and said it didn't find previously submitted data was sufficient to approve the treatment for respiratory distress syndrome in premature infants.

The latest request from the FDA focused on the test used to determine the drug's shelf-life and whether the commercial product would be comparable to the product used in the studies. The company said it is unlikely to satisfy the requirement with existing data and gain approval soon keeping in mind the new standard.

In a statement the company said, "This new standard represents a significant hurdle for approval of Surfaxin. Discovery Labs believes that the information provided to the FDA for the meeting demonstrates comparability and supports Surfaxin approval."

The company is determining its next course of action of either more discussions with the FDA or an appeal. They are also planning to focus on their KL4 resurfactant and aerosolization platforms which are potential aerosolized treatments for the condition.

Discovery shares went down 50% to a new 52-week low of 52 cents in after-hours trading.