To overcome that obstacle and eliminate the patient adherence issue, one potential solution has been to provide a noninvasive depot of antibiotic that can be released over time to replace the multiple doses of antibiotic.
At the University of Pittsburgh, however, engineers have developed a thermoresponsive, hydrogel-controlled release drug containing microspheres, or SoliDrop.
SoliDrop is liquid at room temperature, but “forms a comfortable, pliable, formfitting nondegradable hydrogel after exposure to body temperature in conjunctival cul-de-sac,” he said. The hydrogel material “is loaded with controlled-release microspheres capable of delivering a wide range of drugs for varying lengths.”
Preliminary rabbit studies using SoliDrop with glaucoma drug brimonidine demonstrated good efficacy over 28 days. The goals of the latest study were to evaluate the efficacy of the drug-delivery system and its ability to release moxifloxacin at a high concentration over a short period.
“We wanted to provide a proof of principle that the placement of a single drop of moxifloxacin controlled release hydrogel drop into the conjunctival cul-de-sac can provide effective prophylaxis against bacterial endophthalmitis in a rabbit model,” Romanowski said.
Leaving Morgan V. Fedorchak, PhD (developer of the technology) to “do her magic,” Romanowski said she was able to develop microspheres that have “a quick burst release over 60 minutes, and while there were other microspheres that will allow a release over 7 days.”
There were eight rabbits in each of three groups: a moxifloxacin microsphere group, a blank hydrogel group, and a control group that was instilled with 10 drops of moxifloxacin over 24 hours; they then injected Staphylococcus aureus into the anterior chamber.
Researchers began instilling moxifloxacin starting an hour before inoculation, every 15 minutes, then again right before inoculation and once after inoculation, and four more times post-inoculation over 24 hours. The hydrogel depot was placed 60 minutes before inoculation.
At 24 hours post-injection, the researchers performed a slit lamp exam, and then cultured the aqueous and vitreous for bacterial strains. Both the hydrogel implant and the control moxifloxacin eyes had no evidence of endophthalmitis.
The blank hydrogel eyes, however, all developed endophthalmitis. Further clinical studies are needed to confirm these initial results, Romanowski said.
Eric Romanowski, MS
E: [email protected]
This article was adapted from Romanowski’s AAO 2017 presentation. He has no financial disclosures.