Kuentz, Martin
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Kuentz, Martin
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- PublikationLipophilicity and hydrophobicity considerations in bio-enabling oral formulations approaches | a PEARRL review(Wiley, 04/2019) Ditzinger, Felix; Price, Daniel J.; Ilie, Alexandra Roxana; Koehl, Niklas; Jankovic, Sandra; Tsakiridou, Georgia; Aleandri, Simone; Kalantzi, Lida; Holm, Rene; Nair, Anita; Saal, Christoph; Griffin, Brendan; Kuentz, Martin [in: Journal of Pharmacy and Pharmacology]01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationTowards a better understanding of solid dispersions in aqueous environment by a fluorescence quenching approach(Elsevier, 25.10.2018) Jankovic, Sandra; Kuentz, Martin; Aleandri, Simone [in: International Journal of Pharmaceutics]Solid dispersions (SDs) represent an important formulation technique to achieve supersaturation in gastro-intestinal fluids and to enhance absorption of poorly water-soluble drugs. Extensive research was leading to a rather good understanding of SDs in the dry state, whereas the complex interactions in aqueous medium are still challenging to analyze. This paper introduces a fluorescence quenching approach together with size-exclusion chromatography to study drug and polymer interactions that emerge from SDs release testing in aqueous colloidal phase. Celecoxib was used as a model drug as it is poorly water-soluble and also exhibits native fluorescence so that quenching experiments were enabled. Different pharmaceutical polymers were evaluated by the (modified) Stern-Volmer model, which was complemented by further bulk analytics. Drug accessibility by the quencher and its affinity to celecoxib were studied in physical mixtures as well as with in SDs. The obtained differences enabled important molecular insights into the different formulations. Knowledge of relevant drug-polymer interactions and the amount of drug embedded into polymer aggregates in the aqueous phase is of high relevance for understanding of SD performance. The novel fluorescence quenching approach is highly promising for future research and it can provide guidance in early formulation development.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationLipophilicity and hydrophobicity considerations in bio‐enabling oral formulations approaches – a PEARRL review(Wiley, 08/2018) Ditzinger, Felix; Price, Daniel; Ilie, Alexandra Roxana; Koehl, Niklas; Jankovic, Sandra; Tsakiridou, Georgia; Aleandri, Simone; Kalantzi, Lida; Holm, Rene; Nair, Anita; Saal, Christoph; Griffin, Brendan; Kuentz, Martin [in: Journal of Pharmacy and Pharmacology]Objectives This review highlights aspects of drug hydrophobicity and lipophilicity as determinants of different oral formulation approaches with specific focus on enabling formulation technologies. An overview is provided on appropriate formulation selection by focussing on the physicochemical properties of the drug. Key findings Crystal lattice energy and the octanol–water partitioning behaviour of a poorly soluble drug are conventionally viewed as characteristics of hydrophobicity and lipophilicity, which matter particularly for any dissolution process during manufacturing and regarding drug release in the gastrointestinal tract. Different oral formulation strategies are discussed in the present review, including lipid‐based delivery, amorphous solid dispersions, mesoporous silica, nanosuspensions and cyclodextrin formulations. Summary Current literature suggests that selection of formulation approaches in pharmaceutics is still highly dependent on the availability of technological expertise in a company or research group. Encouraging is that, recent advancements point to more structured and scientifically based development approaches. More research is still needed to better link physicochemical drug properties to pharmaceutical formulation design.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationTemperature-Induced Surface Effects on Drug Nanosuspensions(Springer, 02/2018) Aleandri, Simone; Schönenberger, Monica; Niederquell, Andreas; Kuentz, Martin [in: Pharmaceutical Research]Purpose 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 Zeitschrift
- PublikationStudy of rheology and polymer adsorption onto drug nanoparticles in pharmaceutical suspensions produced by nano milling(Elsevier, 2017) Negrini, Renata; Aleandri, Simone; Kuentz, Martin [in: Journal of Pharmaceutical Sciences]Nanosuspensions 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