title: Optimizing flurbiprofen-loaded NLC by central composite factorial design for ocular delivery.
abstract: The purpose of this study was to design and optimize a new topical delivery system for ocular administration of flurbiprofen (FB), based on lipid nanoparticles. These particles, called nanostructured lipid carriers (NLC), were composed of a fatty acid (stearic acid (SA)) as the solid lipid and a mixture of Miglyol(®) 812 and castor oil (CO) as the liquid lipids, prepared by the hot high pressure homogenization method. After selecting the critical variables influencing the physicochemical characteristics of the NLC (the liquid lipid (i.e. oil) concentration with respect to the total lipid (cOil/L (wt%)), the surfactant and the flurbiprofen concentration, on particle size, polydispersity index and encapsulation efficiency), a three-factor five-level central rotatable composite design was employed to plan and perform the experiments. Morphological examination, crystallinity and stability studies were also performed to accomplish the optimization study. The results showed that increasing cOil/L (wt%) was followed by an enhanced tendency to produce smaller particles, but the liquid to solid lipid proportion should not exceed 30 wt% due to destabilization problems. Therefore, a 70:30 ratio of SA to oil (miglyol + CO) was selected to develop an optimal NLC formulation. The smaller particles obtained when increasing surfactant concentration led to the selection of 3.2 wt% of Tween(®) 80 (non-ionic surfactant). The positive effect of the increase in FB concentration on the encapsulation efficiency (EE) and its total solubilization in the lipid matrix led to the selection of 0.25 wt% of FB in the formulation. The optimal NLC showed an appropriate average size for ophthalmic administration (228.3 nm) with a narrow size distribution (0.156), negatively charged surface (-33.3 mV) and high EE (∼90%). The in vitro experiments proved that sustained release FB was achieved using NLC as drug carriers. Optimal NLC formulation did not show toxicity on ocular tissues.
authors.affiliation: Department of Physical Chemistry, Faculty of Pharmacy, Institute of Nanoscience and Nanotechnology, University of Barcelona, Avenida Joan XXIII s/n, E-08028 Barcelona, Spain. eligonzalezmi@ub.edu
authors.forename: E
authors.initials: E
authors.lastname: Gonzalez-Mira
authors.forename: M A
authors.initials: MA
authors.lastname: Egea
authors.forename: E B
authors.initials: EB
authors.lastname: Souto
authors.forename: A C
authors.initials: AC
authors.lastname: Calpena
authors.forename: M L
authors.initials: ML
authors.lastname: García
mesh_terms: D000287:Administration, Topical; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage*; D003460:Crystallization; D004337:Drug Carriers / Q000009:adverse effects / Q000737:chemistry*; D004355:Drug Stability; D005123:Eye / Q000187:drug effects; D005480:Flurbiprofen / Q000008:administration & dosage*; D008055:Lipids / Q000009:adverse effects / Q000737:chemistry*; D049329:Nanostructures / Q000009:adverse effects / Q000737:chemistry* / Q000648:ultrastructure; D009883:Ophthalmic Solutions / Q000009:adverse effects / Q000737:chemistry*; D010316:Particle Size; D011817:Rabbits
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D004337:Drug Carriers; D008055:Lipids; D009883:Ophthalmic Solutions; D005480:Flurbiprofen