(Reuters) - U.S. drugmaker Pfizer Inc <PFE.N> posted a better-than-expected quarterly profit on Tuesday, driven by higher sales of pneumonia vaccine Prevnar and arthritis drug Xeljanz.
The company lowered its 2018 revenue expectation to between $53 billion and $55 billion, from $53.5 billion to $55.5 billion, due to a strengthening dollar.
Net income rose to $3.87 billion, or 65 cents per share, in the second quarter, from $3.07 billion, or 51 cents per share, a year earlier. [nBw4zNDZka]
Excluding special items, the company 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.
(Reporting by Tamara Mathias in Bengaluru; Editing by Sriraj Kalluvila)