A nationwide shortage of erythromycin ophthalmic ointment is causing some ophthalmologists to try alternative antibiotic therapies to treat superficial ocular infections, whereas others say the shortage won't affect them much because they prefer other therapies.
To save the limited supply of erythromycin for neonatal use, the FDA, the Centers for Disease Control and Prevention, the American Academy of Ophthalmology, and the American Society of Cataract and Refractive Surgery have recommended that general ophthalmologists turn to azithromycin (AzaSite, Inspire Pharmaceuticals) as an alternative ophthalmic ointment. Clinicians also are are finding bacitracin and gentamicin to be suitable alternatives.
The erythromycin supply shortage is being attributed to a change in manufacturers. The ointment is manufactured by Fera Pharmaceuticals—which recently acquired rights to the product—and by Bausch & Lomb. Both companies are working to increase production, although shortages are anticipated in both the 1- and 3.5-gram tubes, according to the FDA.
Bausch & Lomb spokeswoman Elizabeth Harness Murphy said the company shifted to 24/7 production of single- and multi-dose units of erythromycin in early September and expects to meet demand this month. "We are extremely aware of the importance of this medicine to the market, and we're doing everything in our power to alleviate the shortage," she said.
Eric D. Donnenfeld, MD, a New York-based refractive surgeon, said he routinely uses azithromycin instead of erythromycin to treat blepharitis and meibomian gland dysfunction, in part because it works as both an anti-inflammatory and an antibiotic and also because it is FDA-approved for use once a day (after using twice a day the first 2 days).
"It's well-tolerated like erythromycin, and it has many of the same characteristics. It does almost all the things erythromycin does but does it better," he said.
"I actually like azithromycin better than erythromycin because it's more broad-spectrum, it has a greater concentration power, and it's not an ointment so it doesn't blur the vision," Dr. Donnenfeld continued. "It adheres to the lid better without blocking the oil glands themselves."
Terrence P. O'Brien, MD, professor of ophthalmology, holder of the Charlotte Breyer Rodgers Distinguished Chair in Ophthalmology, and co-director of the Ocular Microbiology Laboratory, Bascom Palmer Eye Institute, University of Miami, said he has found increasing resistance to erythromycin and has switched to using azithromycin or bacitracin. He said Staphylococcus epidermidis, found in the normal flora on the lids and lashes, and S aureus, a more virulent pathogen on the ocular surface, were exhibiting resistance to erythromycin.
"We were finding rates of resistance as high as 70% among those ocular isolates of staphylococci," he said. "Because of that, our usage had dwindled prior to this shortage, and we were using alternative agents."
Erythromycin is commonly prescribed "nonspecifically" for upper respiratory and ear infections, according to Dr. O'Brien.
"That's where the resistance is really built up," he said. Dr. O'Brien said he likes bacitracin because, unlike erythromycin, it is not available in pill form for systemic use, therefore there is less selection pressure for resistance.
"While azithromycin has been used systemically, more favorable tissue pharmacodynamics allow higher concentrations achievable than with erythromycin and a higher therapeutic index," he said.
Bacitracin has been around since the late 1940s, and has a spectrum of activity similar to penicillin, Dr. O'Brien explained.
"It too, however, is insoluble and only available in ointment form," he said.