Biopharmaceutical evaluation of ophthalmic excipients using in vitro and ex vivo corneal models

doctoral thesis

• Title (croatian): Biofarmaceutska ispitivanja oftalmičkih ekscipijensa na in vitro i ex vivo modelima rožnice
• Author: Marina Juretić
• Mentor: Ivan Pepić (mentor)
• Committee member: Anita Hafner (predsjednik povjerenstva)
• Committee member: Ana Mornar Turk (član povjerenstva)
• Committee member: Marjana Durrigl (član povjerenstva)
• Granter: University of Zagreb; Faculty of Pharmacy and Biochemistry; (Department of pharmaceutical technology); Zagreb
• Defense date and country: 2019-10-17, Croatia
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Pharmacy; Pharmacy
• Universal decimal classification (UDC): 615 - Pharmacology. Therapeutics. Toxicology

Abstract

Bioavailability of topical ophthalmic products is substantially determined by the type and concentration of excipients.
In addition to the use in conventional ophthalmic formulations, excipients are increasingly utilized in the development
of innovative nanosystem-based ophthalmic formulations, in which excipients are supramolecularly organized into
nano-sized structures, which can specifically interact with the anterior eye segment barriers and enhance the drug eyerelated
bioavailability. Evaluation of the drug transcorneal permeability is a critical step in predicting eye-related
bioavailability of topical ophthalmic drugs. In this thesis, the effect of unimers and supramolecular aggregates of the
ophthalmic excipients on corneal barrier properties and ophthalmic drug permeability was evaluated, using in vitro
(HCE-T cell-based) and/or ex vivo (excised porcine cornea) corneal models. Histological and functional
characterization of the in vitro corneal model revealed variability of the HCE-T barrier phenotype, which highlights
the important aspects to be considered in the further model development. HCE-T cell-based model of a specific
histological structure, but showing improved barrier tightness and a very strong correlation of ophthalmic compounds
permeability with excised porcine cornea, was shown to be suitable for the ophthalmic drug permeability evaluation
considering the influence of ophthalmic excipients. Biopharmaceutical evaluation of melatonin-loaded nanosystems
using HCE-T cell-based models revealed significant influence of chitosan on nanosystem biopharmaceutical
properties. In lecithin/chitosan nanoparticles the presence of chitosan ensured mucoadhesive properties and prolonged
melatonin release, controlling melatonin in vitro transcorneal permeation, which may provide enhanced melatonin
eye-related bioavailability and therapeutic effect. The in vitro/ex vivo evaluation of the effect of nonionic surface
active ophthalmic excipients on the ophthalmic drug permeability revealed their concentration-dependent
permeability-decreasing effect, which was potentially related to the association of ophthalmic drugs with selfaggregates
of surface active ophthalmic excipients. The results of this thesis provide valuable insight into the effect of
ophthalmic excipients on ophthalmic drug transcorneal permeability, which may contribute to more directed and
economical development of both conventional and innovative topical ophthalmic products.

Abstract (croatian)

Bioraspoloživost topikalnih oftalmičkih pripravaka značajno je određena vrstom i udjelom eskcipijensa. Osim u
konvencionalnim oftalmičkim oblicima, ekscipijensi primjenu pronalaze i u izradi inovativnih oftalmičkih oblika
temeljenih na nanosustavima za dostavu lijeka. Interakcija ekscipijensa rezultira tvorbom supramolekulskih struktura
nanodimenzija, koje mogu povećati bioraspoloživost lijeka u oku prevladavanjem barijera prednjeg segmenta oka.
Ispitivanje permeabilnosti lijeka preko barijere rožnice ključan je korak u određivanju bioraspoloživosti topikalnih
oftalmičkih lijekova. Cilj ovog doktorskog rada je bio ispitati utjecaj unimera i supramolekulskih agregata oftalmičkih
ekscipijensa na barijerna svojstva rožnice i permeabilnost oftalmičkih lijekova korištenjem in vitro HCE-T modela
epitela humane rožnice i ex vivo tkivnog modela rožnice svinje. Histološkom i funkcionalnom karakterizacijom in
vitro modela utvrđena je određena varijabilnost fenotipa HCE-T barijere, što ukazuje na potrebu za dodatnom
karakterizacijom čimbenika uzgoja s utjecajem na barijerna svojstva modela. HCE-T model specifične histološke
strukture, ali čvršćih međustaničnih veza te vrlo dobre korelacije permeabilnosti oftalmičkih supstancija s ex vivo
tkivnim modelom rožnice svinje, pokazao se prikladnim za ispitivanje učinka oftalmičkih ekscipijensa na
permeabilnost oftalmičkih lijekova. Biofarmaceutskom karakterizacijom nanosustava za dostavu melatonina
korištenjem in vitro HCE-T modela utvrđen je značajan utjecaj kitozana na biofarmaceutska svojstva nanočestica. U
slučaju lecitinsko-kitozanskih nanočestica kitozan je osigurao mukoadhezivna svojstva, produljeno oslobađanje i
kontroliranu permeaciju melatonina preko HCE-T barijere rožnice, što može pospješiti bioraspoloživost i terapijski
učinak melatonina. U in vitro/ex vivo ispitivanjima uočeno je smanjenje permeabilnosti oftalmičkih lijekova ovisno o
vrsti i koncentraciji neionskih površinski aktivnih oftalmičkih ekscipijensa, što je potencijalno uzrokovano
interakcijom lijeka s agregatima površinski aktivnih oftalmičkih ekscipijensa. Rezultati ovog doktorskog rada značajan
su doprinos razumijevanju učinka oftalmičkih ekscipijensa na permeabilnost oftalmičkih lijekova, što može pridonijeti
usmjerenijem i ekonomičnijem razvoju konvencionalnih i inovativnih topikalnih oftalmičkih pripravaka.

• Keywords: ophthalmic drugs; ophthalmic excipients; surfactants; nanosystems; drug permeability; eye-related bioavailability; in vitro and ex vivo corneal models; HCE-T
• Keywords (english): oftalmički lijek; oftalmički ekscipijensi; površinski aktivni ekscipijensi; nanosustavi; permeabilnost; bioraspoloživost; in vitro i ex vivo modeli rožnice; HCE-T
• Language: english
• URN:NBN: urn:nbn:hr:163:952606
• Study programme: Title: Pharmacy and biochemistry; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor znanosti (doktor znanosti)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-04-08 07:31:19