Pfizer Inc. (PFE), the world's biggest drugmaker, on Wednesday reported strong second-quarter earnings on booming sales of cholesterol and depression drugs and merger-related cost savings.

Cholesterol medicine Lipitor (search), the world's top selling drug, again led the way with sales up 17 percent to $2.36 billion.

Of Pfizer's key drugs, only Viagra (search) — under pressure from new competition — posted a decrease from a year earlier. Sales of the impotence treatment were off 7 percent at $389 million.

New York-based Pfizer posted net profit of $2.86 billion, or 38 cents per share. That compared with a loss of $3.59 billion, or 48 cents per share, a year-earlier, when the company took charges of almost $5.8 billion to account for costs of its $56 billion acquisition of Pharmacia Corp.

Excluding special items, including $747 million in charges related to the 2003 Pharmacia acquisition, Pfizer earned 47 cents per share, in line with the average forecast of 46 cents per share among analysts polled by Reuters Estimates.

Quarterly revenue grew 24 percent to $12.27 billion, helped by a new slate of products from Pharmacia and by the benefit of the weak dollar.

Sales of antidepressant Zoloft (search) surged 25 percent to $789 million, while Neurontin for epilepsy soared 32 percent to $782 million.

In June Pfizer was ordered to pay $240 million after pleading guilty to criminal health-care fraud for promoting Neurontin for unapproved uses, such as to treat pain and migraines.

Arthritis drug Celebrex (search), acquired in the Pharmacia acquisition, had sales of $728 million for the quarter.