UPDATE 3-Johnson & Johnson profit beat fueled by strength in pharma business

* Pharma unit sales rise 20 pct, driven by cancer drug growth

* Co pares 2018 sales forecast

* Shares up marginally premarket (Adds analyst comment, updates share move)

July 17 (Reuters) - Johnson & Johnson topped analysts' estimates for quarterly profit and revenue on Tuesday, as strong demand for cancer drugs Zytiga and Darzalex more than made up for declining sales of blockbuster treatment Remicade.

Shares of the U.S. healthcare giant, which also trimmed its full-year sales forecast, were volatile in premarket trading. After initially slipping, they recovered to trade marginally up at $125.80.

Sales in pharmaceuticals, the company's biggest unit, surged nearly 20 percent to $10.35 billion in the second quarter, as the company focuses on its better performing unit while selling-off some businesses such as diabetes care devices.

The company's multiple myeloma drug, Darzalex, had sales of $511 million, above analysts' consensus estimate of $453 million. Prostate cancer drug Zytiga sales came in at $909 million, above the consensus of $794 million, according to Jefferies.

But the company, whose products range from band-aids to cancer medicines and joint replacement devices, remained under pressure from falling sales of its blockbuster rheumatoid arthritis drug, Remicade, which faces competition from cheaper copies.

Sales of the drug fell 13.7 percent drop in the latest reported quarter, after sliding 16.9 percent in the first quarter.

J&J has vowed to appeal a Missouri jury verdict that earlier this month ordered the company to pay a record $4.69 billion to 22 women, who had claimed their cancer was caused by J&J talc products.

Net earnings rose to $3.95 billion, or $1.45 per share, in the second quarter, from $3.83 billion, or $1.40 per share, a year earlier.

Excluding items, the company reported a profit of $2.10 per share, beating analysts' average estimate of $2.07.

Total sales rose to $20.83 billion from $18.84 billion a year ago, above analysts' estimates of $20.39 billion.

The healthcare conglomerate said it expects full-year sales of $80.5 billion to $81.3 billion, compared with a prior estimate of $81.0 billion to $81.8 billion. The company cited a strengthening dollar for the trim.

"This (foreign exchange) was a key driver of the company lowering FY sales guidance and sets a potentially cautious tone for earnings season for the US Pharma space, especially those with greater ex-US exposure," Credit Suisse's Vamil Divan said.

International revenue for J&J rose 11.8 percent in the reported quarter, and accounted for nearly half of its total sales. J&J said it now expects adjusted earnings of $8.07 to $8.17 per share, compared with an earlier forecast of $8.00-$8.20 per share. (Reporting by Manas Mishra in Bengaluru; Editing by Sriraj Kalluvila)