Exploration of in vitro drug release testing methods for saquinavir microenvironmental pH modifying buccal films

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Buccal films containing a pH modifying excipient may be able to increase bioavailability of drugs with pH-dependent solubility such as saquinavir. Access to suitable in vitro drug release testing methods may facilitate buccal formulation development. This study aimed to explore two release testing methods for characterising buccal films and to elucidate the relationship between microenvironmental pH (pHM, i.e. the pH around the swelling films) and saquinavir release. The Franz diffusion cell method was applicable to investigate the effect of hydroxypropyl methylcellulose (HPMC) grade on saquinavir release. Films containing HPMC K3 LV had a faster saquinavir release than films containing HPMC K100 LV. A UV/Vis imaging method was developed to visualise saquinavir release and pHM changes during the initial dissolution. Within 5 min, the pHM decreased from 6.8 to around 5.4 for HPMC K100 LV-based films containing 11.1 % or 16.6 % (w/w) malic acid. Subsequently, the pHM increased due to increasing concentrations of saquinavir. An increase in malic acid content led to a faster saquinavir release. The combination of methods may be broadly applicable for excipient screening in development of buccal formulations. The imaging approach holds promise for characterizing other pH modifying formulation principles.

Original languageEnglish
Article number105867
JournalEuropean Journal of Pharmaceutical Sciences
Number of pages10
Publication statusPublished - 2021

Bibliographical note

Funding Information:
Shaolong He acknowledges the China Scholarship Council ( 201708510087 ) for financial support and the technical support from Søren Michael Nielsen, Rita Wulff Rasmussen, Jens Graff, Mette Frandsen and Dorthe Ørbæk.

    Research areas

  • Drug release testing method, Franz diffusion cell, Microenvironmental pH, Saquinavir buccal film, UV/Vis imaging

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