2020, Ditzinger, Felix, Wieland, Rebecca, Statelova, Marina, Vertzoni, Maria, Holm, Rene, Kuentz, Martin

Hot melt extrusion of amorphous systems has become a pivotal technology to cope with challenges of poorly water-soluble drugs. Previous research showed that small molecular additives with targeted molecular interactions enabled introduction of a polyelectrolyte matrix into hot melt extrusion that would otherwise not be possible to process due to the unfavorable properties upon heating of the pure polymer. Carboxymethyl cellulose sodium (NaCMC) with lysine or alternatively meglumine led to modified polymeric matrices that showed adequate processability by hot melt extrusion and yielded stable amorphous formulations. The investigated formulations, including fenofibrate as a model drug, were characterized by attenuated total reflectance Fourier transform infrared spectroscopy, differential scanning calorimetry, and viscosity measurements after aqueous dispersion. Further biopharmaceutical assessment started with biorelevant nonsink dissolution testing followed by a pharmacokinetic in vivo study in rats. The in vitro assessment showed superiority of the lysine-containing formulation in the extent of in vitro supersaturation and overall drug release. In accordance with this, the in vivo study also demonstrated increased exposure of the amorphous formulations and in particular for the system containing lysine. In summary, the combination of polyelectrolytes with interacting additives presents a promising opportunity for the formulation of poorly water-soluble drugs.

2018-07, Jankovic, Sandra, Tsakiridou, Georgia, Ditzinger, Felix, Koehl, Niklas, Price, Daniel, Ilie, Alexandra Roxana, Kalantzi, Lida, Kimpe, Kristof, Holm, Rene, Nair, Anita, Griffin, Brendan, Saal, Christoph, Kuentz, Martin

Objectives Solubility parameters have been used for decades in various scientific fields including pharmaceutics. It is, however, still a field of active research both on a conceptual and experimental level. This work addresses the need to review solubility parameter applications in pharmaceutics of poorly water‐soluble drugs. Key findings An overview of the different experimental and calculation methods to determine solubility parameters is provided, which covers from classical to modern approaches. In the pharmaceutical field, solubility parameters are primarily used to guide organic solvent selection, cocrystals and salt screening, lipid‐based delivery, solid dispersions and nano‐ or microparticulate drug delivery systems. Solubility parameters have been applied for a quantitative assessment of mixtures, or they are simply used to rank excipients for a given drug. Summary In particular, partial solubility parameters hold great promise for aiding the development of poorly soluble drug delivery systems. This is particularly true in early‐stage development, where compound availability and resources are limited. The experimental determination of solubility parameters has its merits despite being rather labour‐intensive because further data can be used to continuously improve in silico predictions. Such improvements will ensure that solubility parameters will also in future guide scientists in finding suitable drug formulations.

2019, Ditzinger, Felix, Scherer, Uta Maria, Schönenberger, Monica, Holm, Rene, Kuentz, Martin

Hot melt extrusion (HME) has become an essential technology to cope with an increasing number of poorly soluble drug candidates. However, there is only a limited choice of pharmaceutical polymers for obtaining suitable amorphous solid dispersions (ASD). Considerations of miscibility, stability, and biopharmaceutical performance narrow the selection of excipients, and further technical constraints arise from needed pharmaceutical processing. The present work introduces the concept of molecularly targeted interactions of a coformer with a polymer to design a new matrix for HME. Model systems of dimethylaminoethyl methacrylate copolymer, Eudragit E (EE), and bicarboxylic acids were studied, and pronounced molecular interactions were demonstrated by 1H, 13C NMR, FTIR spectroscopy, as well as by different techniques of microscopic imaging. A difference was shown between new formulations exploiting specifically the targeted molecular interactions and a common drug−polymer formulation. More specifically, a modified matrix with Malic acid exhibited a technical extrusion advantage over polymer alone, and there was a benefit of improved physical stability revealed for the drug fenofibrate. This model compound displayed greatly enhanced dissolution kinetics from the ASD formulations. It can be concluded that harnessing molecularly designed polymer modifications by coformers has much potential in solid dispersion technology and in particular regarding HME processing.

2018-08, 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

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.