Black box warnings on fluoroquinolone

The US Food and Drug Administration has asked manufacturers of fluoroquinolone antimicrobial drugs to place a boxed warning on their labeling advising of the increased risk of tendinitis and tendon rupture and provide a Medication Guide to patients about possible side effects.

Fluoroquinolones are used for the treatment or prevention of certain bacterial infections. Drugs in this class include Bayer's Cipro/Ciprobay (ciprofloxacin), which lost patent protection in 2006. The German drugmaker also makes another affected antibiotic, Avalox/Avelox (moxifloxacin). The agent is sold by local licensee Schering-Plough in the USA, where it earned $75.0 million in second-quarter 2008. The recently-launched fluoroquinolone Factive (gemifloxacin mesylate) was approved in May last year and is seen as a key revenue driver for USA-based Oscient.

The antibiotic Levaquin (levofloxacin) was one of the top seven best performing drugs for US health care major Johnson & Johnson last year. Other fluoroquinolones include Depomed's ProQuin XR, a once-daily, extended-release formulation of the off-patent antibiotic ciprofloxacin and Merck & Co's Noroxin/Chibroxin (norfloxacin), which lost patent protection in 2000.