AstraZeneca just got some breathing room for its blockbuster heartburn drug Nexium.

The company said today that it will give Ranbaxy, the Indian generics manufacturer, exclusive rights to sell a generic version of AstraZeneca’s best-selling drug — but not until 2014, six months before the main patent on Nexium expires.

There had been some concern that Ranbaxy could bring a generic version of the blockbuster to market as early as this year, which would have caused some serious trouble for AstraZeneca. Sales of the drug topped $5.22 billion last year.

While a bit of legal saber-rattling to that effect continues from Teva and Dr. Reddy’s, the market clearly thinks the deal with Ranbaxy is a very good sign — shares were up more than 10% at one point today in U.K. trading, Bloomberg reports.

Analysts were also pleased. Citi’s Kevin Wilson called the deal “better than expected,� noting that he’d expected a settlement that would have allowed Ranbaxy to bring a generic to market in 2012.

Credit Suisse’s Steve Plag called the deal “unremittingly good news.� But, in a mention characteristic of the troubles facing the industry these days, Plag added that AstraZeneca still faces patent challenges to its antipsychotic Seroquel, the company’s second-best-selling drug.