Cumberland Pharmaceuticals has been hit by the news that regulators will need more time to review Acetadote, causing share prices to fall.

Although the drug is already approved to treat acetaminophen overdoses, the company hoped to gain approval for it be used as a treatment for patients with non-acetaminophen acute liver failure.

The US Food and Drug Administration informed the Tennessee-based firm that the review has been extended by three months and a decision may not arrive until December.

Jefferies & Co analyst David Windley told that the delay puts the decision dangerously close to the expiration of exclusivity from Acetadotes orphan drug status on 23 January 2011.

Share prices fell 8.6% ($0.52) to $5.50 in Monday morning trading as a result.