Pfizer, the world’s largest drug company, is close to announcing plans for construction of a new inpatient clinical trial center in conjunction with Yale University and the city of New Haven, a company spokesman said.

The proposed center would be used for phase-I clinical drug trials, the first stage of government-mandated tests that must be performed before a drug can reach the market. Such tests administer experimental medicines to human volunteers under close observation.

Official plans are still being drafted, however.

“We are trying to get our I’s dotted and our T’s crossed,” Pfizer spokesman Stephen Lederer said. An announcement will be made “very soon,” he said.

Henry Fernandez, New Haven’s economic development administrator, said an announcement would not be made until the city, the University and Pfizer all settle on specific arrangements.

“We’re all being quiet until we have a plan that we all agree on,” Fernandez said.

Clinical trial centers exist at a number of hospitals throughout the United States and around the world, Lederer said. They help facilitate accurate testing for medicines approved for human clinical trial by the federal government. The new clinical trial center could have up to 50 beds and would accommodate around the clock subject surveillance.

Lederer said Pfizer considered a number of possible sites in Connecticut and elsewhere but decided to locate near Yale because of the school’s excellent reputation in medical imaging technology.

“We wanted to find somewhere where we could collaborate with a very good hospital,” Lederer said. “And something found at Yale that is of enormous value is imaging technology.”

Imaging technology has become sufficiently sophisticated that it can now tell researchers not only if the drug is working, but also how much of the drug is in someone’s system, and how quickly the body gets rid of it, Lederer said.

The proposed center would be able to focus largely on experimental drugs for the brain and central nervous system where close visual monitoring is especially helpful.

The innovative research in the area of medical imaging technology by James Duncan, a professor of diagnostic radiology and electrical engineering, helped draw Pfizer to Yale. Last spring, Duncan helped secure the Biomedical Engineering Program’s largest grant ever — $7.1 million — to look at epilepsy and further Yale’s research into medical imaging technologies. Pfizer found Duncan’s studies on imaging analysis and representation — turning data into scientifically useful information — very useful.

Pfizer also found New Haven attractive because the company’s research and development headquarters is located in nearby Groton and has a satellite campus in New London. Pfizer currently employs a total of 6,000 workers between its two Connecticut sites.

“All partners have played an important role,” Fernandez said. “We’re not quite there yet, but we will be soon,” he said.

Pfizer currently has research and development facilities in Groton, Conn.; Ann Arbor, Mich.; and La Jolla, Calif., as well as Europe and Asia. The company reported $26.3 billion in sales globally during 2001, $1.7 billion more that its nearest competitor, GlaxoSmithKline. Pfizer’s best-known prescription products include the anti-impotence drug Viagra, anti-depressant Zoloft, and Lipitor, for high cholesterol.