DURHAM, N.C. – Inspire Pharmaceuticals (Nasdaq: ISPH) took two steps Monday designed to bolster its future.

After announcing the close of a stock offering that brought in $115 million, later disclosed in a filing with the Securities and Exchange Commission that it had extended an anti-takeover agreement with private equity firm Warburg Pincus.

Inspire and Pincus agreed to extend a so-called “standstill agreement” that they had first signed on July 20, 2007. The new agreement, signed Aug. 4, extends the hostile takeover defense through Aug. 4, 2012.

Under the agreement, Warburg and “certain of its affiliates” agree not to increase beyond either the lesser of two percentages of Inspire stock: 32.5 percent of “our voting securities on a fully diluted basis and 34.9 percent of our then outstanding voting securities,” Inspire said in a statement.

Earlier after the markets closed, Inspire said it had sold all 22.2 million of the shares it offered at $4.50. Deutsche Bank Securities, which handled the stock offering, purchased an additional 3.3 million shares.

The company initially announced an $80 million offering.

Inspire shares closed at $4.72, up 15 cents.