Generic competition and pricing pressures weighed on AstraZeneca's sales in the third quarter, ahead of a key challenge to its top-selling cholesterol drug Crestor in the U.S. marketplace.

A weaker dollar provided a prop to Britain's second-biggest drugmaker, with sales at the reported level up 4 percent at $8.21 billion (5.13 billion pounds), while in local currencies they fell 2 percent.

The result was slightly better than expected. Analysts had, on average, forecast sales of $8.16 billion, according to Thomson Reuters I/B/E/S.

The company also said on Thursday it had raised its full-year target for core earnings per share (EPS), which excludes some items, to between $7.20 and $7.40, from $7.05 to $7.35, largely on currency movements.

Analysts said the market had been anticipating higher EPS due to foreign exchange effects, and the broadly in-line quarterly numbers left the shares just 0.3 percent higher at 1000 GMT, slightly lagging the European drugs sector <.SXDP>.

A one-off gain from the $1.8 billion sale of dental and surgical unit Astra Tech to Dentsply was excluded from core results, which saw pretax profit flat at $3.08 billion in the quarter, equivalent to EPS up 14 percent at $1.71.

Chief Executive David Brennan said the results, against a tough backdrop, were in line with the group's own expectations.

AstraZeneca faces a major challenge to Crestor from the end of next month, when generic copies of Pfizer's
market-leading cholesterol pill Lipitor are due to hit the U.S. market.

Results from a head-to-head study last month failed to show Crestor was better than Lipitor in reducing clogging in coronary arteries.

Finance chief Simon Lowth acknowledged that generic Lipitor would limit Crestor's pricing power but argued it would still have a strong position for treating higher-risk heart patients.

For now, Crestor is selling well -- its sales rose 14 percent to $1.66 billion in the quarter -- but investors fear it could lose momentum just as revenue from other blockbusters such as heartburn pill Nexium is also falling.

At the same time, all drugmakers are being forced to cut prices across developed-world markets, particularly in Europe. Lowth told reporters he expected even more price pressure from cash-strapped governments in Europe next year and further mid-single digit percentage price cuts.

EMERGING MARKETS SLOWER

In a bid to find new areas of growth, AstraZeneca is pushing hard into emerging markets, where demand for medicines has been growing strongly.

However, its sales in these markets rose only 7 percent in the third quarter, down from 10 percent in the second quarter and 13 percent in the first, partly due to generic competition to Crestor and the antipsychotic drug Seroquel in Brazil.

New heart drug Brilinta -- launched in the United States in August -- sold slowly, with third-quarter global sales of just $13 million, of which $11 million was U.S. stockbuilding.

Mark Clark of Deutsche Bank said overall results were reassuring but some points could cause investors concern.

In addition to slower emerging markets growth and modest Brilinta sales, he noted U.S. Crestor growth of 20 percent was based partly on price rises that were unlikely to be repeated.

Over the next five years, analysts forecast a steady decline in overall sales at the London-based group because of heavy losses to generics -- a trend that contrasts with cross-town rival GlaxoSmithKline , where sales are set to increase.

AstraZeneca has a relatively few new drugs to replace them and its pipeline reputation took a knock on Thursday with a news that the experimental asthma drug MEDI-528 was being scrapped.

A day earlier, U.S. regulators delayed a verdict on whether to approve a new diabetes drug, dapagliflozin, that the group is developing with Bristol-Myers Squibb .

Given its weak long-term outlook, some analysts have speculated that AstraZeneca may seek a sizeable acquisition to help fill the sales gap -- but Lowth repeated the company line that it was not looking at major buys.

AstraZeneca trades on the lowest multiple of any major European drug company, with the shares fetching around 7 times this year's expected earnings against more than 12 times for GSK, which reported results on Wednesday.

(Editing by Erica Billingham)