Apparent solubility of drugs in biorelevant media using image based single particles

Štukelj, Jernej (author), Kristl, Julijana (mentor), Svanbäck, Sami (comentor)

Two physicochemical properties, solubility and stability, play a major role in determining the developability of a drug. These two properties are highly dependent on the solid-state form of a drug. Therefore, rapid and accurate solubility measurements and solid-state characterization in early stages of drug development process are crucial for optimal decision making. A newly developed image based single particle analysis method capable of acquiring solubility from individual drug crystals now holds a vast potential for being implemented in drug development process. In this thesis, possibilities for using the image based method beyond equilibrium solubility measurements were investigated. First, the applicability of the image based method for measuring apparent solubility of α and amorphous form of indomethacin in biorelevant media was tested. The set-up was calibrated using set of ten compounds (R2 = 0.9590). The Kruskal-Wallis and Mann-Whitney statistical test results showed that the method was capable of differentiating α, γ and amorphous form of indomethacin in all five buffers used. The average solubility ratio of α to γ form particles was constant in all solvents (3.33 ± 0.47), whereas, average solubility ratio of amorphous to γ form was not. It was the biggest in fed state simulated intestinal fluid (229.6), where the concentration of surfactants was above their critical micellar concentration. Moreover, the method was also able to measure and distinguish between true apparent solubility of two differently prepared and stored amorphous forms of indomethacin. Next, the image based method was coupled with Time-Gated Raman spectroscopy. The simultaneous acquisition of image data and Raman spectra was not achieved, due to the laser light saturating the camera. Therefore, measurements of amorphous particles were done separately. With the image based method, changes in dissolution slope were observed indicating a solid-state change. On the other hand, results obtained with the online Raman measurements were hard to interpret due to not knowing the exact position of the focal point. In summary, these results show that the image based method could be used for quick estimation of drug behaviour in the gastrointestinal tract. Furthermore, the true apparent solubility of metastable and unstable forms and, with some improvements, also solventmediated solid-state changes of amorphous forms could be assessed with the image based single particle analysis method.

• Language: English
• Keywords: image based single particle analysis, biorelevant media, indomethacin, solubility, Time-Gated Raman spectroscopy
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FFA - Faculty of Pharmacy
• Place of publishing: Ljubljana
• Publisher: [J. Štukelj]
• Year: 2017
• Number of pages: IX, 63 f.
• PID: 20.500.12556/RUL-107386
• UDC: 544.351.3:615.011(043.3)
• COBISS.SI-ID: 4412529
• Publication date in RUL: 09.04.2019

Secondary language

• Language: Slovenian
• Title: Navidezna topnost učinkovin v bioloških medijih s slikovno analizo posameznih delcev

Abstract

Dve fizikalno-kemijski lastnosti, topnost in stabilnost, sta ključni za uspešen razvoj zdravilne učinkovine v končno obliko. Obe lastnosti sta v tesni povezavi s trdnim stanjem učinkovine. Zato sta hitra in natančna določitev topnosti ter trdnega stanja v začetnih fazah razvojnega procesa ključnega pomena za sprejemanje optimalnih odločitev. Nova metoda slikovne analize posameznih delcev, s katero lahko določimo topnost iz posameznih kristalov spojine, ima velik potencial, za vključitev v razvojni proces zdravil. V tej nalogi smo raziskali možnosti uporabe metode slikovne analize, ki presegajo določitev zgolj absolutne toposti. Najprej smo preverili uporabnost metode za določanje navidezne topnosti α in amorfne oblike indometacina v biorelevantnih medijih. Napravo smo umerili z naborom desetih substanc (R2 = 0.9590). Rezultati statističnih testov Kruskall-Wallis in Mann- Whitney so pokazali, da je metoda slikovne analize zmožna določiti in razlikovati med topnostmi α, γ in amorfne oblike indometacina v vseh petih uporabljenih medijih. Razmerje povprečnih topnosti delcev α proti γ je bilo konstantno v vseh medijih (3.33 ± 0.47). Razmerje povprečnih topnosti amorfne napram obliki γ ni bilo konstantno. Razmerje je bilo najvišje v neteščem simuliranem črevesnem mediju (229.6), kjer je vsebnost surfaktantov presegala njihovo kritično micelarno koncentracijo. V nadaljevanju smo z metodo slikovne analize uspeli določiti in razlikovati med topnostmi dveh različnih amorfnih oblik. Metodo slikovne analize smo združili s časovno-pogojeno Ramansko spektroskopijo, vendar sočasno zajemanje slik in Ramanskega signala ni bilo mogoče zaradi premočne laserske svetlobe, ki je zasitila detektor optične kamere. Zaradi tega smo meritve izvedli ločeno. Z metodo slikovne analize smo opazili spremembo naklona zmanjševanja delcev, ki nakazuje spremembo trdnega stanja. Interpretacija rezultatov, ki smo jih dobili iz »online« Ramanskih meritev, pa je bila otežena zaradi nepoznavanja natančne pozicije žarišča laserja. Rezultati kažejo, da bi metodo slikovne analize lahko uporabili za hitro oceno obnašanja zdravilne učinkovine v gastrointestinalnem traktu. Prav tako je z metodo slikovne analize posameznih delcev mogoče določiti pravo navidezno topnost delno stabilnih in nestabilnih oblik učinkovin. Z nekaj izboljšavami pa bi bilo moč opazovati tudi spremembe trdnega stanja, ki se dogajajo med raztapljanjem amorfnih oblik učinkovin.

• Keywords: slikovna analiza posameznih delcev, biorelevantni mediji, indometacin, Ramanska spektroskopija