UPDATE 2-Pfizer beats profit estimates but lowers 2018 revenue forecast

* Co raises 2018 adj. EPS forecast to reflect buybacks

Xeljanz, Lipitor sales beat estimates (Adds drug sales, background and share movement)

July 31 (Reuters) - Pfizer Inc topped Wall Street estimates for quarterly profit on Tuesday, driven by higher sales of its cholesterol and arthritis drugs, but the biggest U.S. drugmaker lowered its full-year revenue forecast due to a stronger dollar.

The company's rheumatoid arthritis drug, Xeljanz, reported sales of $463 million for the second quarter, beating consensus estimates of $432 million, according to brokerage SunTrust Robinson Humphrey.

Sales of cholesterol-lowering medicine Lipitor came in at $521 million, easily topping estimate of $466 million.

Earlier this month, Pfizer said it would defer price hikes on around 40 of its drugs for no more than six months, after Chief Executive Officer Ian Read spoke with U.S. President Donald Trump.

Since then, other major drugmakers, including Merck & Co , Eli Lilly and Novartis, have made similar announcements.

On Tuesday, Pfizer said it now expects 2018 revenue of between $53 billion and $55 billion, compared with a prior forecast of $53.5 billion to $55.5 billion.

The company is the latest U.S. drugmaker to trim its annual revenue forecast due to a strengthening dollar. Johnson & Johnson also slightly lowered its full-year sales forecast, citing the strong currency.

Pfizer has said it would reorganize itself and create a separate consumer healthcare unit, a business the New York-based company has been trying to sell since last year.

Net income rose 26 percent to $3.87 billion, or 65 cents per share, in the second quarter.

Excluding special items, Pfizer earned 81 cents per share, beating analysts' average estimate of 74 cents, according to Thomson Reuters I/B/E/S.

Revenue rose 4.4 percent to $13.47 billion, ahead of expectations of $13.31 billion.

The company raised its full-year adjusted earnings per share forecast to between $2.95 and $3.05, from $2.90 to $3.00 earlier.

Pfizer said the new forecast reflects $6.1 billion worth of share repurchases already completed in 2018.

Shares of the New York-based company fell slightly to $38.45 in premarket trading. (Reporting by Tamara Mathias in Bengaluru; Editing by Sriraj Kalluvila)