Salix Pharmaceuticals reported strong third-quarter revenue late Tuesday as demand for the company’s best-selling drug Xifaxan continued to grow.

The Raleigh company also announced that it is adding two new products to its drug portfolio by acquiring privately-held Oceana Therapeutics for $300 million in cash.

The deal, which is expected to close by the end of the year, is Salix’s second major acquisition in 2011. The company earlier acquired the rights to Relistor, a drug that treats constipation in patients taking pain medicines.

Salix, which focuses on drugs used to treat gastrointestinal ailments, is one of the few small drug companies based in the Triangle with actual products and revenue. The company has about 450 employees, including 200 in North Raleigh.