Pfizer, the world’s biggest drug maker, posted its fourth-quarter profit to have missed analysts’ estimates on costs from its acquisition of Wyeth and projected lower-than-expected earnings in 2010.

However, company’s Chief Financial Officer Frank D'Amelio quoted that responsible spending is helping build demand for its medicines in developed and emerging markets.

It reports a more than doubled profit of $767 million, or 10 cents a share, from $266 million, or 3 cents a share, the previous year, when results were hit by a $2.3 billion legal settlement related to the marketing of the Bextra painkiller.

Earnings excluding one-time items registered 49 cents a share, falling 2 cents short of the average estimate of 14 analysts surveyed by Bloomberg News. Revenue increased 34 percent, to $16.5 billion from $12.3 billion.

Pfizer is reported to have completed its $68 billion acquisition of Wyeth in October, which was initiated for the replacement of the billions in revenue that would have been lost when its top-selling cholesterol pill, Lipitor, faces generic competition next year.

Pfizer augurs its spending this year to be of $19 billion to $20 billion for sales, general and administrative expenses, about $2 billion more than Leerink Swann analyst Seamus Fernandez had estimated.