Just two weeks after it expressed interest in outbidding a rival to buy ClinPhone, Quintiles said Monday that it was out of the running. Quintiles of Durham helps drug makers test and sell new medicines.

The decision leaves the door open for Parexel International, which had agreed to acquire ClinPhone for $182 million in cash.

Quintiles spokesman Dick Jones declined to say why Quintiles had decided it wouldn't try to outbid Parexel for ClinPhone. "It was worth taking a look," he said.

Quintiles had worked with ClinPhone in the past and considered the software maker a strategic fit. ClinPhone's technology helps select people for drug tests and collects data from the tests.

Rather than looking for a deal with another company, Quintiles will focus on in-house technology, Jones said.

A year ago, Quintiles announced a joint venture with Thermo Fisher Scientific to develop technology that promises to make clinical trials less expensive. The joint venture, Cenduit, provides Internet services, such as automating the delivery of clinical-trial supplies and randomly assigning patients to certain tests.

Cenduit, which is based at Quintiles' headquarters in Durham, provides services at five locations, including in Bangalore, India, and Basel, Switzerland.

The largest contract drug researcher by revenue, Quintiles generated more than $2 billion in revenue last year. Quintiles has been privately held since a $1.75 billion buyout five years ago.

With demand for clinical testing rising, Quintiles has been expanding. A new headquarters is going up at Interstate 40 and Page Road in Durham, and hiring is brisk.

In the next five years, Quintiles plans to add about 5,000 employees to its worldwide work force of 21,000. Headcount at its corporate headquarters is expected to double to 2,000.