Key Takeaways

  • Provectus Biopharmaceuticals and VisiRose received a patent award for a topical eye drop formulation of RBS API for treating Gram-positive bacterial keratitis, including drug-resistant strains.
  • The RBS API drop formulation is light-independent, meaning it can potentially be self-administered by patients with the same use pattern as existing prescription antibiotic drops, but for resistant-organism infections those drugs increasingly cannot clear.

Provectus Biopharmaceuticals and VisiRose were issued US Patent No. 12,661,335, titled “Halogenated Xanthene-Containing Topical Anti-Gram-Positive Bacterial Ophthalmic Composition and Method,” covering a topical eye drop formulation of RBS API for treating Gram-positive bacterial keratitis, including drug-resistant strains, such as methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus.

The data underlying the patent show that this formulation of RBS API is able to kill resistant Gram-positive bacteria and eradicate biofilms in the dark, with no light step required, which opens the door to a self-administered eye drop with the same use pattern as existing prescription antibiotic drops, but for resistant-organism infections those drugs increasingly cannot clear. This may lead to a meaningful shift in treatment paradigm for patients with bacterial keratitis caused by drug-resistant Gram-positive organisms, chronic and recurrent blepharitis and conjunctivitis, and contact lens-associated infections.

The patent specifically covers:

  • Light-independent killing: claims cover antibacterial activity in the substantial absence of activating light.
  • Resistant-pathogen coverage: claimed effective concentrations span methicillin- and vancomycin-resistant Staphylococcus aureus and drug-resistant Enterococcus faecalis and Enterococcus faecium. These are among the organisms where first-line antibiotics are failing.
  • Biofilm eradication: chronic, recurrent ocular infections are often biofilm-driven and tolerant to standard antibiotics, including linezolid. The claimed composition eradicates biofilms in both light and dark conditions.
  • Defined, tear-compatible formulation: claims fix concentration (about 0.2 to 50 μg/mL), pH (6.5 to 7.6, matching normal human tear pH), viscosity, and osmolality. These are specifications aimed at ocular tolerability and FDA formulation review.
  • Wide safety margin: in preclinical testing, the cytotoxicity threshold in mammalian cells sat well above the concentrations needed to kill resistant bacteria, the gap a potential topical product needs to support repeat dosing.