OPHTHALMIC QUINOLONES SHOULD UNDERGO VEHICLE CONTROLLED TRIALS
OPHTHALMIC QUINOLONES SHOULD UNDERGO VEHICLE CONTROLLED TRIALS for the treatment of conjunctivitis, according to a discussion by the Ophthalmic Drugs Subcommittee of FDA's Anti-Infective Drugs Advisory Committee. At a Dec. 17 meeting, the subcommittee recommended that "a study design which is both appropriate and essential for bacterial conjunctivitis should include a vehicle controlled trial" as well as more traditional active control studies. The recommendation was part of a package of advice and suggestions to improve trial designs for testing ophthalmic quinolones used in the treatment of conjunctivitis and corneal ulcers. The point of departure for the subcommittee discussion was a schematic of a trial design for quinolones presented by Wiley Chambers, MD, Group Leader of FDA's Ophthalmic, Dermatologic, and Gynecologic Drugs team. The schematic, Chambers explained, represented his personal preferences and was not an official FDA document. Chambers suggested that firms conduct both a vehicle controlled and an active clinical controlled trial before receiving approval. He noted three possible clinical endpoints for measuring efficacy in these trials -- a quinolone could be approved if trials demonstrated that it was effective at eliminating clinical symptoms of conjunctivitis, or if it reduced infection according to a bacterial culture, or if it demonstrated superior rates of recovery over conventional therapies. Under the FDAer's plan a drug could not be approved if on any day of a vehicle controlled trial the drug's efficacy was shown to be statistically inferior to that of the placebo therapy. Allergan Pharmaceuticals consultant and Georgetown University ophthamology professor Michael Lemp, MD, questioned the vehicle controlled requirement. "It is questionable," Lemp said, "whether it is even possible to design an adequate vehicle controlled study using an aqueous vehicle...because of the irrigating effects with frequent dosing and the presence of preservatives in the solutions...These are significant confounding factors in terms of the results...In addition...there is the reluctance to enroll patients with more serious conditions in placebo controlled studies..." The subcommittee's suggestions on how to define patient populations and clinical endpoints for quinolone/conjunctivitis trials appeared to be less controversial. Members were unanimous in recommending that FDA require future conjunctivitis trials to distinguish between patients who suffer from bacterial conjunctivitis and those who are diagnosed with the related eyelid syndromes blepharitis and blepharoconjunctivitis. They also appeared to agree that any well controlled clinical trial would require improvement or cure in both bacteriological and clinical terms. Recognizing "there is currently no approved ocular medication which is also generally accepted for the treatment of corneal ulcers," the subcommittee suggested that sponsors should be allowed to establish efficacy for this indication by comparing cure rates to those recorded for "fortified" ophthalmic solutions in the medical literature.
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