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Classification of promiscuous glass-formers: Limitations of differential scanning calorimetry
Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för farmaci.
Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för farmaci.ORCID-id: 0000-0002-8917-2612
Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för farmaci. Astra Zeneca.
(engelsk)Manuskript (preprint) (Annet vitenskapelig)
HSV kategori
Forskningsprogram
Farmaceutisk vetenskap
Identifikatorer
URN: urn:nbn:se:uu:diva-390254OAI: oai:DiVA.org:uu-390254DiVA, id: diva2:1341193
Tilgjengelig fra: 2019-08-07 Laget: 2019-08-07 Sist oppdatert: 2019-08-14
Inngår i avhandling
1. Molecular Mechanisms Influencing the Performance of Amorphous Formulations for Poorly Water-Soluble Drugs
Åpne denne publikasjonen i ny fane eller vindu >>Molecular Mechanisms Influencing the Performance of Amorphous Formulations for Poorly Water-Soluble Drugs
2019 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Crystallisation is a concern for amorphous formulation because it compromises the solubility-enhancing benefit gained from amorphisation. Traditionally, amorphous formulation had been designed primarily based on trial-and-error approach. The success rate for amorphous formulation is unimpressive, due to a poor understanding of the formulation itself, especially with regard to its crystallisation behaviour. Therefore, this thesis aimed to propose a strategic approach for rational design of amorphous formulations, as opposed to the trial-and-error approach. This can be achieved by understanding what drives the crystallisation of amorphous drug, and when and how the amorphous drug crystallises. The information can guide the selection of drugs, excipients and preparation method to achieve amorphous formulations with favourable features.

In the first part of the thesis, a systematic protocol was proposed to identify mechanisms via which crystallisation takes place when amorphous drug is dissolved. The stabilisation strategy of supersaturation produced upon dissolution of amorphous drug was then recommended depending on the crystallisation mechanisms. A molecular dynamics (MD) simulations was used to understand drug-polymer interaction during supersaturation. It was revealed that hydrogen bond interaction is an important in stabilising supersaturation. The factors affecting glass-forming ability and long-term physical stability such as preparation method and humidity were then highlighted in the second study. A follow-up study was performed to elucidate the potential complications in using a standardised differential scanning calorimetry to classify promiscuous glass formers into any specific glass-forming ability/glass stability class. In the subsequent study, the effect of physical aging and/or crystallisation of amorphous drugs during storage on supersaturation potential was addressed. It was shown that, minor crystallisation of amorphous drug upon storage did not have a significant impact on the supersaturation potential during dissolution. Instead, the crystallisation pathway of the amorphous drug during dissolution plays a more important role in determining the supersaturation behaviour of some drugs. Finally, the impact of (i) drug loading on physical stability, supersaturation, drug/polymer miscibility, and (ii) the physical aging and/or crystallisation upon storage on supersaturation potential of spray-dried solid dispersions with HPMC-AS were discussed in the last study. It was observed that the effect of drug loading on physical stability and supersaturation, and the effect of physical aging and/or crystallisation during storage on supersaturation potential is highly drug-dependent. Similarly, the stabilisation effect of HPMC-AS varied across model drugs, drug loadings and crystallisation pathways (i.e. in solid or during dissolution). The Flory-Huggins interaction parameter calculated using MD simulations revealed good miscibility between the drugs and HPMC-AS at drug loadings investigated. In the presence of water molecules, various structural organizations of the drugs and HPMC-AS complexes were observed. Taken together, this thesis provides an improved understanding of crystallisation behaviour of amorphous formulations, which is useful to guide a rational design of amorphous formulations.

sted, utgiver, år, opplag, sider
Uppsala: Acta Universitatis Upsaliensis, 2019. s. 73
Serie
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Pharmacy, ISSN 1651-6192 ; 276
Emneord
Amorphous formulation, crystallisation, supersaturation, glass-forming ability, physical stability, glass stability, spray-dried solid dispersion, dissolution, promiscuous glass former, poorly-soluble drug, solid-to-solid, solution-mediated, particle-associated
HSV kategori
Forskningsprogram
Farmaceutisk vetenskap
Identifikatorer
urn:nbn:se:uu:diva-390579 (URN)978-91-513-0717-6 (ISBN)
Disputas
2019-09-27, Room B21, Biomedical Center, Husargatan 3, Uppsala, 13:15 (engelsk)
Opponent
Veileder
Tilgjengelig fra: 2019-09-04 Laget: 2019-08-14 Sist oppdatert: 2019-09-17

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