CHICAGO - As much as doctors would like to deny it, subtle attention from friendly drug sales representatives can have a big impact on what drugs they prescribe, according to two U.S. studies published on Monday.

"Physicians underestimate their own vulnerability. They think they are smarter ... but they are not trained in recognizing this kind of manipulation," said Adriane Fugh-Berman, a Georgetown University Medical Center researcher and co-author of one of the studies.

Fugh-Berman teamed with Shahram Ahari, a former drug representative for Eli Lilly and Co., who now works at the University of California, San Francisco's school of pharmacy.

Their study, which appears in the Public Library of Science journal PLoS Medicine, details the elaborate methods used by drug company sales representatives to make friends and influence drug sales.

"Reps scour a doctor's office for objects - a tennis racquet, Russian novels, '70s rock music, fashion magazines, travel mementos or cultural or religious symbols - that can be used to establish a personal connection with the doctor," Fugh-Berman and Ahari wrote.

"A friendly physician makes the rep's job easy because the rep can use the 'friendship' to request favors in the form of prescriptions.

"Physicians who view the relationship as a straightforward goods-for-prescriptions exchange are dealt with in a businesslike manner. Skeptical doctors who favor evidence over charm are approached respectfully, supplied with reprints from the medical literature and wooed as teachers," they wrote.

Sales representatives also ingratiate themselves by lining up paid speaking engagements for doctors and arranging educational grants to those who frequently prescribe their drugs.

The study comes as drugmakers are smarting over the public revelation this month from an AstraZeneca drug sales representative, who said in a unauthorized newsletter to staff: "There is a big bucket of money sitting in every office. Every time you go in, you reach your hand in the bucket and grab a handful."

An AstraZeneca spokeswoman said the manager was fired and the company was looking into the incident, which she said violates a core value of serving patients.

Quick visit, lasting effects
Another study found that even a brief visit by a drug sales rep could have a powerful impact.

The study analyzed surveys done by a market research firm that chronicled a doctor's intention to prescribe the epilepsy drug gabapentin during the period of 1995 to 1999, when it was sold by Warner-Lambert under the brand name Neurontin.

Pfizer Inc., which acquired that unit in 2000, paid a $240 million fine four years later for illegal promotion of the drug for unapproved uses such as migraines or pain.

The surveys involved 116 visits to 97 doctors.

They found that after 46 percent of the visits, the doctors said they intended either to prescribe gabapentin more often or to recommend it to colleagues more often.

"The remarkable thing is how effective a very brief visit by a drug representative - most often less than five minutes - can be in influencing physicians' choices to use a drug for an unapproved indication," Dr. Michael Steinman of the San Francisco Veterans Affairs Medical Center said in a statement.

Besides free drug samples, salespeople often bring gifts, lunch for the doctor or office staff, new pens and coffee mugs. "The doctor feels subtly, even subconsciously, indebted to the representative," Steinman said.