Pfizer, the world's largest drug maker, said fourth-quarter earnings plunged 50 percent, but still beat analyst expectations despite revenue lost to generic versions of its best-selling anti-cholesterol drug Lipitor.

Net income for Pfizer (NYSE:PFE) slid 50 percent to $1.43 billion, or only 19 cents a share, from the year-earlier quarter. Still, they beat analysts' lowered expectations by three cents,.

Fourth quarter revenues fell about 4 percent to $16.7 billlion from $17.3 billion because of lower prescription drug sales but were offset by sales of other items. Sales of animal health products rose 13 percent.

For the year, New York-based Pfizer said revenue rose a meager 1 percent to $67.4 billion; full-year net rose 21 percent to $10 billion, or $1.27 a share, from $8.3 billion, or $1.02, a year earlier.

Pfizer faced rough going last year because a loss on patent exclusivity for Lipitor promised to take a bite out of revenue. Generic makers headed by Israel's Teva now compete with their own products. Pfizer countered with an increase at its animal health wing, as well as infant nutrition products, while reducing costs nine percent.

CEO Ian Read said the company plans to spin off the animal health and nutrition units in an effort to double-down on prescription drug sales. For 2012, Pfizer said it expects revenue to rise about 21 percent to as much as $62.5 billion, with net income ranging between $1.37 and $1.52 a share.

Pfizer shares closed up 5 cents to $21.45 on Tuesday.