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Publikation Temperature-Induced Surface Effects on Drug Nanosuspensions(Springer, 02/2018) Aleandri, Simone; Schönenberger, Monica; Niederquell, Andreas; Kuentz, MartinPurpose The trial-and-error approach is still predominantly used in pharmaceutical development of nanosuspensions. Physicochemical dispersion stability is a primary focus and therefore, various analytical bulk methods are commonly employed. Clearly less attention is directed to surface changes of nanoparticles even though such interface effects can be of pharmaceutical relevance. Such potential effects in drug nanosuspensions were to be studied for temperatures of 25 and 37°C by using complementary surface analytical methods. Methods Atomic force microscopy, inverse gas chromatography and UV surface dissolution imaging were used together for the first time to assess pharmaceutical nanosuspensions that were obtained by wet milling. Fenofibrate and bezafibrate were selected as model drugs in presence of sodium dodecyl sulfate and hydroxypropyl cellulose as anionic and steric stabilizer, respectively. Results It was demonstrated that in case of bezafibrate nanosuspension, a surface modification occurred at 37°C compared to 25°C, which notably affected dissolution rate. By contrast, no similar effect was observed in case of fenofibrate nanoparticles. Conclusions The combined usage of analytical surface methods provides the basis for a better understanding of phenomena that take place on drug surfaces. Such understanding is of importance for pharmaceutical development to achieve desirable quality attributes of nanosuspensions.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Study of rheology and polymer adsorption onto drug nanoparticles in pharmaceutical suspensions produced by nano milling(Elsevier, 2017) Negrini, Renata; Aleandri, Simone; Kuentz, MartinNanosuspensions provide a drug delivery approach to cope with erratic absorption of poorly water-soluble compounds. Despite extensive research over the last years, there are still open pharmaceutical challenges so it is often unclear how quality attributes such as viscosity and physical stability are generated, which requires a more thorough study of the colloidal structures and interactions in nanosuspensions. In this study, diffusing wave spectroscopy and microfluidics-based rheology were used for the first time to assess pharmaceutical nanosuspensions that were obtained by wet milling. Further sample characterization following centrifugation was based on optical rotatory dispersion and conductivity experiments. Ketoconazole was selected as model drug in the presence of sodium dodecyl sulfate and hydroxypropyl cellulose as anionic and steric stabilizer, respectively. The results unexpectedly showed that the investigated nanosuspensions did not behave as Einstein-like suspensions because a viscosity decrease was evidenced for increased drug load. This effect was attributed to the polymer that formed a dominating network in the bulk solution from where adsorption occurred onto particle surfaces. This depletion of bulk polymer caused the observed rheological finding. Further colloidal research should be invested into different pharmaceutical nanosuspensions to gain a more complete structural understanding and to harness their full technological potential.01A - Beitrag in wissenschaftlicher Zeitschrift