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Thermally reactive N-(2-hydroxypropyl)methacrylamide (HPMA) amphiphiles for drug solubilisation

Curtis, Anthony

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Thermally active polymers, can respond structurally to temperature changes, making them interesting as potential drug delivery vehicles. Polymers of N-(3-aminopropyl) methacrylamide hydrochloride (APMA) are cationic with primary amine groups in their structure, which have been explored in biomedical applications via post-polymerisation modifications. In this work, we synthesised amphiphilic APMA monomers using hydrophobic pendant groups via conjugation onto their primary amine group. The pendant groups chosen in this study were palmitoyl, dansyl and cholesteryl moieties. The amphiphilic monomers were subsequently copolymerized with N-(2-hydroxypropyl)methacrylamide (HPMA) using varied monomer feed ratios resulting in a thermoresponsive system. The ability of the resultant aggregates in aqueous solution to encapsulate and liberate model drugs (e.g., propofol, griseofulvin and prednisolone) was then determined. Our data showed that the HPMA based formulations were capable of loading the model drug molecules inside their lipophilic core; HPMAco-(APMA-Dansyl 2%) exhibited the largest drug encapsulation ability. Subsequently, poly(ethylene glycol) (PEG) was incorporated into the intrinsic polymer structure. This resulted in a more rapid drug release profile, whereby 100% of griseofulvin and prednisolone were liberated after only 4 h, which was only 5% and 10% before the PEG inclusion, respectively. Similarly, propofol showed 70% liberation from the polymer aggregate after 24 h, compared with only 30% liberation pre-PEGylation. These studies give an insight into the potential of the HMPA based amphiphiles as thermally responsive cargo carrier/release systems which could be exploited in the delivery of poorly soluble drugs.


Curtis, A., Alsuraifi, A., Mathew, E., Lamprou, D. A., & Hoskins, C. (2021). Thermally reactive N-(2-hydroxypropyl)methacrylamide (HPMA) amphiphiles for drug solubilisation. International Journal of Pharmaceutics, 601, Article ARTN 120570.

Journal Article Type Article
Acceptance Date Mar 31, 2021
Online Publication Date Apr 2, 2021
Publication Date May 15, 2021
Print ISSN 0378-5173
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 601
Article Number ARTN 120570
Keywords Thermo-responsive polymers; drug delivery; intelligent nanomedicine; smart polymers; drug solubilisation
Publisher URL


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