UPDATE 1-Epocrates shares rise 37.3 percent in debut

* Epocrates shares up 37.3 percent after IPO

* Raises $85.76 million, prices at $16 vs $13-$15 range

* Trading on Nasdaq under symbol "EPOC" (Updates to market close)

NEW YORK, Feb 2 (Reuters) - Shares of Epocrates Inc (EPOC.O), a clinical information provider, rose 37.3 percent in their stock market debut on Wednesday, as investors look forward to the company cashing in on its growing user base.

The shares closed at $21.96 after rising as high as $22.75, or 42 percent above the initial public offering price, on Nasdaq.

Among other services, San Mateo, California-based Epocrates allows healthcare professionals to search for information about drugs, insurance, new products and other healthcare reference data on their mobile phones, according to a filing with U.S. regulators.

"They have a million doctors (registered as users) and a lot of those are free apps, so they will want to monetize those eyeballs and that's what people think will happen here," said Francis Gaskins, president of IPOdesktop.com.

"It's an expectation of internal growth," he added.

Epocrates has been growing its user network and boasts 45 percent of U.S. physicians as clients, the company said in the filing.

In June, Epocrates partnered with Pfizer Inc (PFE.N), the world's biggest drugmaker, to help healthcare providers get access to medical information specialists.

In November, Epocrates bought Modality Inc for $13.8 million to acquire its applications for Apple's iPod Touch and iPhone as well as infrastructure for more applications.

In 2009, the company posted revenue of $93.7 million, 12 percent higher than a year earlier. In the nine months ending on Sept. 30, 2010, Epocrates posted a 20 cent loss per common share on a diluted basis compared to a 7 cent profit in the same period a year earlier, the filing showed.

Epocrates raised about $85.76 million in the IPO on Tuesday -- or roughly 14 percent more than it had expected -- selling 5.36 million shares for $16 each. It had originally planned to sell shares for $13 to $15 each.

The company said it would use proceeds from the offering for general purposes and to pay a preferred stock dividend of about $28.6 million to shareholders, which include venture capital firms Sprout Capital IX, InterWest Partners and Bay City Capital.

Epocrates sold 3.57 million shares, while its shareholders sold 1.79 million shares.

Underwriters on the offering, led by J.P. Morgan Securities and Piper Jaffray & Co, have an option to buy up to 804,000 additional shares. (Reporting by Alina Selyukh. Editing by Robert MacMillan)