Fresh off its two-year anniversary on July 3, the CEO for the largest social networking site for physicians, Sermo, told Medical Economics that increases to its 70,000-doctor membership list has not stalled since its announced partnership with drugmaker Pfizer last year.

Fresh off its two-year anniversary on July 3, the CEO for the largest social networking site for physicians, Sermo, told Medical Economics that increases to its 70,000-doctor membership list has not stalled since its announced partnership with drugmaker Pfizer last year.

“Not slowing at all,” says CEO Daniel Palestrant, who notes that at the time of the Pfizer deal in October, the site had 30,000 members. “We’re still adding about 1,000 to 1,500 doctors a week.”

Sermo is a social networking Web site similar to popular Web destinations MySpace and Facebook, but Sermo is restricted to licensed physicians in the United States. The site’s members meet online and discuss practice management, clinical matters and healthcare issues. “We’ve been astounded by the demographics of our user base,” says Palestrant, who notes that the 45-year-old and older members are heavier users of the site than the younger doctors by a rate of 3 to 1. “We’ve also found the busiest doctors are most attracted to the immediacy of the site.”

While Sermo reports the largest membership, it is by no means the only site of its kind for doctors, which also include iMedExchange, SocialMD, Clinical Village, Within3 and others.

Being the largest, however, the partnership with drugmaker Pfizer raised eyebrows in the press and by some of Sermo’s members who feared they would to be inundated with advertising and marketing and didn’t want the $48.4 billion drug company snooping on their conversations. At the time, Sermo said the deal benefited doctors by offering them comprehensive data on Pfizer products and services.

Despite the apprehension, Sermo continued to add new members and offer new programs since last year--including CME courses, clinical trials and a job posting board. The site also landed $26.7 million in investment funding from a group of investors led by Baltimore-based Legg Mason Capital Management. Palestrant wouldn’t disclose if the site was profitable yet, but that it has met or exceeded its revenue goals.

Palestrant says a consumer-oriented site will be added to Sermo this year, but wouldn’t elaborate on details. He also mentioned hopes to expand the site to include international doctors.