Salix says FDA approves diarrhea drug Fulyzaq

Salix said it plans to start marketing the drug in early 2013. The company said Fulyzaq could have up to five years of marketing exclusivity, meaning similar products won't be approved in that time.

The drug is designed to treat diarrhea in patients with HIV or AIDS who are on anti-retroviral therapy. Salix says many patients who are taking anti-retroviral drugs experience episodic or chronic diarrhea, which can lead to weight loss and affect compliance with the treatment.

Salix said Fulyzaq, or crofelemer, is the first FDA-approved botanical drug that is intended to be taken orally. The active ingredient in the drug is derived from the sap of a tree called Croton lechleri, and is commonly known as "dragon's blood" because of the red color of the sap. The ingredient is isolated and purified after the sap is extracted.

Shares of Salix rose $2.10, or 5.2 percent, to $42.57 as the markets moved higher in midday trading. They peaked for the past year at $55.99 in March, and traded as low as $37.52 in early November.