| Abstract | Bolest suhog oka je multifaktorijalna bolest koju karakterizira nestabilnost i hiperosmolarnost suznog filma te upala
površine oka. Kationske nanoemulzije tipa ulje u vodi (U/V) predstavljaju napredak u liječenju bolesti suhog oka služeći
kao tehnološka platforma za uklapanje slabo topljivih djelatnih tvari, omogućujući pritom njihovo produljeno
zadržavanje na površini oka te istodobnu nadoknadu i stabilizaciju narušenog suznog filma. Cilj ovog doktorskog rada
je razvoj funkcionalne kationske nanoemulzije za liječenje bolesti suhog oka. U tu su svrhu pripravljena dva tipa
nanoemulzija korištenjem mikrofluidizatora: primarne kationske nanoemulzije sa stearilaminom i sekundarne kationske
nanoemulzije s kitozanom. Primarne kationske nanoemulzije s rastućim udjelima stearilamina male su veličine kapljica
(< 100 nm), primjerene disperznosti (PDI ≤ 0,25), pozitivnog zeta-potencijala (3,1-25,5 mV), prikladne pH vrijednosti,
male viskoznosti i površinske napetosti 31,3-35 mN m-1. Pripravljene nanoemulzije stabilne su tijekom petomjesečne
pohrane. Nakon miješanja s disperzijom mucina zapažene su promjene u veličini kapljica i zeta-potencijalu koje ukazuju
na interakciju s mucinom. Takve promjene nisu bile izraženije s povećanjem udjela stearilamina na više od 0,05 % (m/m).
Vijabilnost 3D HCE-T modela iznosila je najmanje 90 % nakon izlaganja pripravljenim formulacijama. Sekundarne
kationske nanoemulzije pripravljene s manjim (NC1: 0,05 %, m/m) i većim (NC2: 0,3 %, m/m) udjelom kitozana veličine
su kapljica približno 180 nm, veće homogenosti (PDI < 0,2) i pozitivnog zeta-potencijala (18,7 i 30 mV). Iako je
formulacija NC1 pokazala bolju stabilnost, ibuprofen je uspješno uklopljen u obje formulacije (INC1 i INC2). Fizičkokemijska
svojstva (pH, viskoznost, osmolarnost i površinska napetost) pripravljenih formulacija unutar su raspona
prikladnog za primjenu na oko. Formulacija INC1 stabilnija je od formulacije INC2 nakon jednomjesečne pohrane.
Bakteriološka filtracija prikladna je metoda sterilizacije pripravljenih formulacija. Oslobađanje ibuprofena iz
pripravljenih formulacija značajno je brže nego iz uljne otopine i suspenzije ibuprofena. Reološka karakterizacija
formulacija pomiješanih s disperzijom mucina pokazala je njihov mukoadhezivni karakter koji, ipak, nije izraženiji kod
formulacije INC2 s većim udjelom kitozana. Ispitivanja na 3D HCE-T modelu i ex vivo modelu rožnice svinje pokazala
su izuzetnu biokompatibilnost INC1 formulacije. Uzimajući u obzir sve rezultate, nanoemulzija s 0,05 % (m/m)
stearilamina i INC1 formulacija ističu se kao vodeće formulacije s velikim potencijalom za liječenje bolesti suhog oka. |
| Abstract (english) | Dry eye disease is a multifactorial disease characterized by tear film instability and hyperosmolarity and ocular surface
inflammation. Oil-in-water (O/W) cationic nanoemulsions represent a progress in dry eye disease treatment serving as a
technological platform for incorporation of poorly soluble drugs, enabling prolonged residence time at the ocular surface
and, at the same time, replenishment and stabilization of compromised tear film. The aim of this doctoral thesis is
development of a functional cationic nanoemulsion for dry eye disease treatment. For this purpose two nanoemulsion
types were prepared using microfluidizer: primary cationic nanoemulsions with stearylamine and secondary cationic
nanoemulsions with chitosan. Primary cationic nanoemulsions with increasing stearylamine weight fraction are
characterized with small droplet size (< 100 nm), low PDI (≤ 0.25), positive zeta-potential (3.1-25.5 mV), appropriate
pH, low viscosity and surface tension 31.3-35 mN m-1. The nanoemulsions are stable after 5-month storage. Changes in
nanoemulsion droplet size and zeta-potential were observed after mixing with mucin dispersion, which indicates
interactions with mucin. However, the changes were not more pronounced with the increase in stearylamine weight
fraction above 0.05 % (w/w). Viability of 3D HCE-T model was at least 90 % after exposure to the prepared formulations.
Secondary cationic nanoemulsions prepared with low (NC1: 0.05 %, w/w) and high (NC2: 0.3 %, w/w) chitosan weight
fraction are characterized with droplet size of around 180 nm, greater homogeneity (PDI < 0.2) and positive zeta-potential
(18.7 and 30 mV). Although the formulation NC1 showed greater stability, ibuprofen was successfully incorporated in
both formulations (INC1 and INC2). The physico-chemical properties (pH, viscosity, osmolarity and surface tension) of
the prepared formulations are within the range acceptable for ophthalmic application. The formulation INC1 is more
stable than the formulation INC2 after 1-month storage. Filtration is an appropriate sterilization method for the prepared
formulations. Ibuprofen release from the prepared formulations is significantly faster than from ibuprofen oil solution
and suspension. Rheological characterization of the formulations mixed with mucin dispersion showed their
mucoadhesive character which, however, is not more pronounced with the formulation INC2 with higher chitosan weight
fraction. The assays performed using 3D HCE-T model and ex vivo porcine cornea model showed remarkable
biocompatibility of the formulation INC1. Taking everything into account, the nanoemulsion with 0.05 % (w/w)
stearylamine and INC1 formulation point out as the lead formulations holding great potential for the treatment of dry
eye disease. |
