UPDATE 1-Amgen quarterly profit tops expectations despite sales decline

(Adds Puerto Rico, sales and cost details, shares)

Oct 25 (Reuters) - Amgen Inc reported higher-than-expected third quarter profit on Wednesday as lower research and other costs and improved operating margins helped offset sales declines in some of its biggest established products.

The world's largest biotechnology company also raised its full-year adjusted earnings forecast to $12.50 to $12.70 per share from its earlier view of $12.15 to $12.65, despite taking a financial hit to its Puerto Rico operations from Hurricane Maria, which devastated the island last month.

Analysts on average were looking for 2017 earnings of $12.58 per share, according to Thomson Reuters data.

Amgen estimated the cost to 2017 earnings of cleanup, repair and restoring full operations in Puerto Rico would be 15 cents to 18 cents per share over the third and fourth quarters, with no expected disruption to product supply.

It does not anticipate the hurricane damage to significantly impact 2018 results.

The company said its Puerto Rico drug substance manufacturing and packaging plants are now fully operational, with formulation/filling and small molecule commercial production to resume by the end of October. However it is still operating with generators due to the extensive damage to the island's electrical grid.

Overall sales declined 1 percent to $5.45 billion, below Wall Street estimates of $5.75 billion.

However research and development spending, cost of sales and selling, general and administrative expenses were all lower in the quarter.

Amgen shares were down 2.5 percent at $173 in extended trading.

Amgen posted third-quarter net profit of $2.02 billion, or $2.76 per share, up from a profit of $2.01 billion, or $2.68 per share, a year ago.

Excluding item, Amgen said it earned $3.27 per share, topping analysts' average expectations by 16 cents. (Reporting by Bill Berkrot; Editing by Meredith Mazzilli)