title: Topical Ocular Drug Delivery to the Back of the Eye by Mucus-Penetrating Particles.
abstract: OBJECTIVE
  Enhanced drug exposure to the ocular surface typically relies on inclusion of viscosity-enabling agents, whereas delivery to the back of the eye generally focuses on invasive means, such as intraocular injections. Using our novel mucus-penetrating particle (MPP) technology, which rapidly and uniformly coats and penetrates mucosal barriers, we evaluated if such drug formulations could increase ocular drug exposure and improve topical drug delivery.
  
  
  METHODS
  Pharmacokinetic (PK) profiling of topically administered loterprednol etabonate formulated as MPP (LE-MPP) was performed in rabbits and a larger species, the mini-pig. Pharmacodynamic evaluation was done in a rabbit model of VEGF-induced retinal vascular leakage. Cellular potency and PK profile were determined for a second compound, KAL821, a novel receptor tyrosine kinase inhibitor (RTKi).
  
  
  RESULTS
  We demonstrated in animals that administration of LE-MPP increased exposure at the ocular surface and posterior compartments. Furthermore using a rabbit vascular leakage model, we demonstrated that biologically effective drug concentrations of LE were delivered to the back of the eye using the MPP technology. We also demonstrated that a novel RTKi formulated as MPPs provided drug levels to the back of the eye above its cellular inhibitory concentration.
  
  
  CONCLUSIONS
  Topical dosing of MPPs of LE or KAL821 enhanced drug exposure at the front of the eye, and delivered therapeutically relevant drug concentrations to the back of the eye, in animals.
  
  
  CONCLUSIONS
  These preclinical data support using MPP technology to engineer topical formulations to deliver therapeutic drug levels to the back of the eye and could provide major advancements in managing sight-threatening diseases.
authors.affiliation: Kala Pharmaceuticals Inc., Waltham, MA, USA.
authors.forename: Lisa R
authors.initials: LR
authors.lastname: Schopf
authors.affiliation: Kala Pharmaceuticals Inc., Waltham, MA, USA.
authors.forename: Alexey M
authors.initials: AM
authors.lastname: Popov
authors.affiliation: Kala Pharmaceuticals Inc., Waltham, MA, USA.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Enlow
authors.affiliation: Kala Pharmaceuticals Inc., Waltham, MA, USA.
authors.forename: James L
authors.initials: JL
authors.lastname: Bourassa
authors.affiliation: Kala Pharmaceuticals Inc., Waltham, MA, USA.
authors.forename: Winston Z
authors.initials: WZ
authors.lastname: Ong
authors.affiliation: Kala Pharmaceuticals Inc., Waltham, MA, USA.
authors.forename: Pawel
authors.initials: P
authors.lastname: Nowak
authors.affiliation: Kala Pharmaceuticals Inc., Waltham, MA, USA.
authors.forename: Hongming
authors.initials: H
authors.lastname: Chen
keywords: choroid; corticosteroids; drug delivery; retina; topical