title: Nanomicellar Topical Aqueous Drop Formulation of Rapamycin for Back-of-the-Eye Delivery.
abstract: The objective of this study was to develop a clear, aqueous rapamycin-loaded mixed nanomicellar formulations (MNFs) for the back-of-the-eye delivery. MNF of rapamycin (0.2%) was prepared with vitamin E tocopherol polyethylene glycol succinate (TPGS) (Vit E TPGS) and octoxynol-40 (Oc-40) as polymeric matrix. MNF was characterized by various parameters such as size, charge, shape, and viscosity. Proton nuclear magnetic resonance ((1)H NMR) was used to identify unentrapped rapamycin in MNF. Cytotoxicity was evaluated in human retinal pigment epithelial (D407) and rabbit primary corneal epithelial cells (rPCECs). In vivo posterior ocular rapamycin distribution studies were conducted in male New Zealand white rabbits. The optimized MNF has excellent rapamycin entrapment and loading efficiency. The average size of MNF was 10.98 ± 0.089 and 10.84 ± 0.11 nm for blank and rapamycin-loaded MNF, respectively. TEM analysis revealed that nanomicelles are spherical in shape. Absence of free rapamycin in the MNF was confirmed by (1)H NMR studies. Neither placebo nor rapamycin-loaded MNF produced cytotoxicity on D407 and rPCECs indicating formulations are tolerable. In vivo studies demonstrated a very high rapamycin concentration in retina-choroid (362.35 ± 56.17 ng/g tissue). No drug was identified in the vitreous humor indicating the sequestration of rapamycin in lipoidal retinal tissues. In summary, a clear, aqueous MNF comprising of Vit E TPGS and Oc-40 loaded with rapamycin was successfully developed. Back-of-the-eye tissue distribution studies demonstrated a very high rapamycin levels in retina-choroid (place of drug action) with a negligible drug partitioning into vitreous humor.
authors.affiliation: Division of Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, 5258 Health Science Building 2464 Charlotte Street, Kansas, Missouri, 64108, USA.
authors.forename: Kishore
authors.initials: K
authors.lastname: Cholkar
authors.forename: Sriram
authors.initials: S
authors.lastname: Gunda
authors.forename: Ravinder
authors.initials: R
authors.lastname: Earla
authors.forename: Dhananjay
authors.initials: D
authors.lastname: Pal
authors.forename: Ashim K
authors.initials: AK
authors.lastname: Mitra
mesh_terms: D060433:Administration, Ophthalmic; D000287:Administration, Topical; D000818:Animals; D001082:Aqueous Humor / Q000378:metabolism*; D002478:Cells, Cultured; D002626:Chemistry, Pharmaceutical / Q000379:methods; D016503:Drug Delivery Systems / Q000379:methods; D004847:Epithelial Cells / Q000378:metabolism; D019573:Epithelium, Corneal / Q000378:metabolism; D006801:Humans; D008297:Male; D009883:Ophthalmic Solutions / Q000008:administration & dosage* / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry; D011817:Rabbits; D055213:Retinal Pigment Epithelium / Q000378:metabolism; D020123:Sirolimus / Q000008:administration & dosage* / Q000737:chemistry*; D014018:Tissue Distribution; D014810:Vitamin E / Q000031:analogs & derivatives / Q000737:chemistry
chemical_list: D009883:Ophthalmic Solutions; D014810:Vitamin E; D011092:Polyethylene Glycols; C014225:tocophersolan; D020123:Sirolimus