Clinipace Worldwide, one of the fastest-growing companies in the Triangle, announced Tuesday that it is acquiring a California contract research organization that will more than double the size of its workforce.

The deal for Paragon Biomedical is the third acquisition Morrisville-based Clinipace has made in the past 18 months. The combined company will employ more than 430 worldwide and is expected to generate revenues of $55 million this year. Terms weren’t disclosed.

Both companies are contract research organizations, or CROs, which help pharmaceutical companies test experimental drugs. Clinipace CEO Jeff Williams said the expertise of the two companies is complementary. While Clinipace has primarily focused on oncology drugs, Paragon specializes in cardiovascular, infectious disease and central nervous system drugs.

Williams said the two companies also tend to target different customer bases. Clinipace focuses on working with small and midsize pharmaceutical and biotechnology companies, and Paragon has had success targeting larger companies.

“Together we’ve got a great story for all of it,” Williams said.

Although demand for CRO services slowed during the recession, the industry has been showing better growth of late.

“There’s no doubt that companies are beginning to invest again in their clinical programs, and I think the whole industry is seeing that,” Williams said.

The Triangle remains the CRO industry’s hub, home to a group of firms that includes Quintiles, INC Research and PRA International.

Clinipace markets itself as a “digital CRO,” as it started out selling software used by pharmaceutical and biotechnology companies to collect and manage data generated during clinical trials. It became a full-service CRO in 2009.

Last month, Inc. Magazine ranked Clinipace 260th on its annual list of the 500 fastest-growing companies in the country, with revenue of $18.5 million last year, up from $1.2 million in 2008, according to the magazine.

Williams said Clinipace’s recent growth reflects in part the fact that the company’s gotten better at competing against other CROs for business.

“We’ve become more effective as a sales and marketing organization, and we’ve gained more credibility with our therapeutic expertise,” he said.

Clinipace, which has nine offices, plans to retain all of Paragon’s employees and keep open its main office in Irvine and its offices in the United Kingdom and India. Clinipace has 64 employees and contractors in North Carolina, the majority of them in Morrisville.

Clinipace’s decision to grow through acquisitions isn’t unusual in the CRO industry. Biotech and pharmaceuticals companies today need to conduct clinical trials in a number of countries to give their drug applications the broadest appeal and to gain access to the necessary patient populations. To conduct such sprawling trials, a small CRO either needs to partner with other CROs or acquire the necessary capacity through acquisitions.

Many choose the latter.

“Historically, this industry seems like it’s in a perpetual state of consolidation,” Williams said. “It’s just the growth model.”

Bracken: 919-829-4548