A court's recent and unexpected decision to invalidate GlaxoSmithKline's (GSK) patent extension for market-leading antibiotic Augmentin (amoxicillin clavulanate) has competitors scrambling to grab its market share and position.

"GSK carved out Augmentin's position as the most efficacious against the broadest range of pathogens and also shared control of the 'appropriate use' positioning," says Tim Baker, vice-president of client strategy at the Zitter Group and primary author of The Management and Use of Anti-Infectives in Managed Care, an opinion survey of 100 health plan medical and pharmacy directors. "There is now an opportunity for other manufacturers to claim that positioning."

Ortho-McNeil's Levaquin (levofloxacin) and Abbott's Biaxin (clarithromycin), and its longer-release formula Biaxin XL, are best poised to gain Augmentin's patients who don't switch to Geneva Pharmaceuticals' generic equivalent of Augmentin. Baker says Levaquin is the most likely inheritor of the Augmentin broad range of efficacy mantle, although

Baker says, "Appropriate use is a huge issue because there are several government-led initiatives to rein in antibiotic use, particularly because there is evidence of growing resistance to macrolides [a type of antibiotic]. They are overused, and because of the price level, they are also a significant burden to payers."

John Lebbos, MD, senior analyst for Decision Resources, also sees growth opportunities for Pharmacia's Zyvox (linezolid) and Aventis' Synercid (quinupristin/dalfopristin), both first-in-class antibiotics designed to treat bacteria resistant to older products. He also predicts that Bristol-Myers Squibb's Tequin (gatifloxacin) will gain market share because of its broad efficacy and once-daily dosing.

"Although public-health campaigns have decreased overprescribing of antibiotics, pharma detailing is still effective in moving market share," says Lebbos. But the Zitter Group's study shows that there may be a backlash to that: 44 percent of health plan respondents believe that Pfizer engages in irresponsible marketing practices because the company's massive sales force could alter physician behavior to increase sales of Zithromax, which they believe is already overused. The survey also found that managed care personnel, based on the perception that the company is more committed to profits than to best practice, felt more inclined to "disadvantage" that product by placing it on its formulary's most expensive tier.

"Price will take on greater importance, as will the equity built into the appropriate-use position," says Baker. "All of a sudden, marketers have an opportunity here. It will be interesting to see how it all plays out."

www.zitter.com