Variable-focus microscopy and UV surface dissolution imaging as complementary techniques in intrinsic dissolution rate determination

Adam Ward, Karl Walton, Karl Box, Jesper Østergaard, Lisa J. Gillie, Barbara R. Conway, Kofi Asare-Addo

Research output: Contribution to journalArticle

8 Citations (Scopus)


This work reports a novel approach to the assessment of the surface properties of compacts used in Surface Dissolution Imaging (SDI). SDI is useful for determining intrinsic dissolution rate (IDR), an important parameter in early stage drug development. Surface topography, post-compaction and post-SDI run, have been measured using a non-contact, optical, three-dimensional microscope based on focus variation, the Alicona Infinite Focus Microscope, with the aim of correlating the IDRs to the surface properties. Ibuprofen (IBU) was used as a model poorly-soluble drug. DSC and XRD were used to monitor possible polymorphic changes that may have occurred post-compaction and post-SDI run. IBUs IDR decreased from 0.033 mg/min/cm2 to 0.022 mg/min/cm2 from 10 to 20 min, respectively, during the experiment. XRD and DSC showed no form changes during the SDI run. The surface topography images showed that a distinct imprint was embossed on the surfaces of some compacts which could affect IDRs. Surface parameter values were associated with the SDI experiments which showed strong correlations with the IDR values. The variable-focus microscope can be used as a complimentary tool in the determination of IDR values from the SDI.
Original languageEnglish
Pages (from-to)139-144
Number of pages6
JournalInternational Journal of Pharmaceutics
Issue number1-2
Early online date22 Jul 2017
Publication statusPublished - 15 Sep 2017


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