Development of an in vitro release test for topical microparticle systems

doctoral thesis

• Title: Razvoj in vitro metode za ispitivanje oslobađanja djelatne tvari iz polimernih mikročestica za topičku primjenu
• Author: Maja Lusina Kregar
• Mentor: Jelena Filipović-Grčić (mentor)
• Committee member: Anita Hafner (predsjednik povjerenstva)
• Committee member: Jasmina Lovrić (član povjerenstva)
• Committee member: Biserka Cetina Čižmek (član povjerenstva)
• Granter: University of Zagreb; Faculty of Pharmacy and Biochemistry; (Department of pharmaceutical technology); Zagreb
• Defense date and country: 2016, Croatia
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Pharmacy; Pharmacy
• Universal decimal classification (UDC): 615; APPLIED SCIENCES. MEDICINE. TECHNOLOGY; Pharmacology. Therapeutics. Toxicology

Abstract

Trenutno ne postoje farmakopejske ili standardne metode i aparature za ispitivanje oslobađanja djelatne tvari iz topikalnih mikročestica. Cilj ovog rada bio je razviti i validirati diskriminatornu in vitro metodu za ispitivanje oslobađanja djelatne tvari iz topikalnih mikročestica, uz korištenje imerzijske ćelije. Za potrebe rada pripremljene su i karakterizirane kitozanske i metakrilatne mikročestice s mupirocinom. Za izradu mikročestica korištena je tehnika sušenja raspršivanjem. Ispitana su sljedeća svojstva mikročestica: učinkovitost uklapanja lijeka, morfologija i veličina čestica, kristalno stanje, termička svojstva, spektralna svojstva, zeta potencijal, higroskopnost te sadržaj vode i ostatnih organskih otapala. Kitozanske i metakrilatne mikročestice s mupirocinom korištene su kao modelni topikalni terapijski sustavi za razvoj in vitro metode za ispitivanje oslobađanja djelatne tvari. Imerzijska ćelija korištena je u kombinaciji s aparaturom s lopaticom. pH i temperatura medija (pH 5,5, 32°C) odabrani su u skladu s fiziološkim uvjetima na koži. Difuzija lijeka odvijala se preko membrane izrađene od smjese celuloznih estera, koja je pokazala nisku adsorpciju lijeka te nizak otpor difuziji lijeka. Nakon početnog zastojnog vremena količina oslobođenog lijeka postala je proporcionalna korijenu iz vremena. Nagib u linearnom području krivulje oslobađanja lijeka korišten je kao mjera brzine oslobađanja. Varijacije u brzini okretanja lopatica (25 o/min, 50 o/min, 100 o/min), visini lopatica (1 cm, 2,5 cm) i volumenu medija za ispitivanje oslobađanja (100 ml, 200 ml) nisu značajno utjecale na brzinu oslobađanja. Analiza kitozanskih mikročestica izrađenih s kitozanima različitih molekulskih masa pokazala je da se kod povećane molekulske mase kitozana smanjuje brzina oslobađanja. S druge strane, brzina oslobađanja bila je veća pri većoj koncentraciji lijeka unutar donorskog odjeljka. Na taj je način pokazana diskriminatornost metode prema razlikama u formulaciji, kao i prema razlikama u koncentraciji uzorka unutar donorskog odjeljka ćelije. Metodom je nadalje potvrđena sličnost serija istog sastava proizvedenih istim procesom. Metoda je validirana u skladu s ICH smjernicama. U sklopu validacije metode potvrđena je njena specifičnost, linearnost, točnost, preciznost i robusnost. Metoda je uspješno primijenjena kod kitozanskih i metakrilatnih čestica, čime je pokazan njen potencijal za karakterizaciju raznih tipova topikalnih čestičnih terapijskih sustava. Razvijena metoda može biti koristan alat u razvoju formulacije kod takvih terapijskih sustava.

Abstract (english)

Currently there are no compendial or standard methods and apparatuses for in vitro release testing of topical microparticles. The aim of this study was to develop and validate a discriminative in vitro release method for topical microparticles using the immersion cell. For the purpose of this study chitosan-based and methacrylate-based microparticles with mupirocin were prepared by spray drying. The following characteristics of the microparticles were examined: encapsulation efficiency, particle size and morphology, crystallinity, thermal properties, spectral properties, surface charge, hygroscopicity, residual organic solvents and water content. Chitosan-based and methacrylate-based microparticles with mupirocin were used as model topical delivery systems for in vitro release method development. The immersion cells were used in combination with paddle dissolution apparatus. The pH and temperature of the release medium (pH 5.5, 32°C) were selected to reflect the physiological skin conditions. Diffusion of the drug occured across a mixed cellulose ester membrane, which demonstrated low drug adsorption and low diffusional resistance. After an initial lag phase the amount of drug released became proportional to the square root of time. The slope in the linear portion of the release curve was used as a measure of release rate. Variations in paddle rotation speed (25 rpm, 50 rpm, 100 rpm), paddle height (1 cm, 2.5 cm) and volume of release medium (100 ml, 200 ml) did not significantly alter the release rates. Appropriate discriminatory power of the method was confirmed as the method was able to detect differences in formulation, as well as differences in drug concentration inside the sample compartment. The analysis of chitosan-based microparticles prepared with chitosans of different molecular weights has shown that the release rate decreases with increasing molecular weight of chitosan. On the other hand, the release rate increased with increasing drug concentration inside the sample compartment. The method was further used to confirm sameness between batches of the same composition prepared by the same process. The method was validated for its specificity, linearity, accuracy, precision and robustness in line with International Conference on Harmonisation (ICH) guidelines. The method was successfully applied both for chitosan-based and methacrylate-based microparticles, which demonstrates its potential application for various types of topical particulate delivery system.

• Keywords: oslobađanje djelatne tvari; mikročestice; topikalna primjena; imerzijska ćelija
• Keywords (english): drug release; microparticles; topical application; immersion cell
• Language: croatian
• URN:NBN: urn:nbn:hr:163:674196
• Study programme: Title: Farmaceutsko-biokemijske znanosti; Study programme type: sveučilišni; Study level: poslijediplomski doktorski; Academic / professional title: doktor znanosti (doktor znanosti)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2016-05-09 12:45:43