Non-linear optical imaging of solid drugs and dosage forms
Written by Andrew. L. Fussell, May Mah, Petra Priemel and Clare J. Strachan
Non-linear Optical Imaging
Non-linear optical imaging is an emerging technique for imaging drugs and dosage forms [1]. Non-linear optical imaging may be used for non-destructive, non-contact imaging of solid drugs and dosage forms. It offers chemical and structural specificity with no requirement for labels, sub-micron spatial resolution (inherent confocal nature), rapid video-rate image acquisition, and the ability to image samples in aqueous environments in situ.
These combined features make non-linear optical imaging unique compared to existing imaging approaches in the pharmaceutical setting and make the technique well suited to a wide range of solid-state formulation and drug delivery analyses. These include imaging chemical and solid-state form distributions in dosage forms, drug release and dosage form digestion, and drug and micro/nanoparticle distribution in tissues and within live cells. While non-linear optical imaging is comparatively well established in the biomedical field, pharmaceutical applications of non-linear optical imaging are much less widely explored.
Pellet Production by Hot Melt Extrusion and Die Face Pelletising
Written by Daniel Treffer and Simone Schrank![Process chain for the production of dosage forms via hot melt extrusion [Internal RCPE Report]](/media/k2/items/cache/780149ddfa09fbd86eb140fe6810d770_M.jpg)
Introduction
The production and manufacturing of solid pharmaceutical products is in need of new technologies to ensure a safe and efficient medical therapy. Hot melt extrusion (HME) is a new and innovative technology in the field of pharmaceutics, which aids to overcome numerous limitations of traditional manufacturing techniques. The benefit of HME is three-fold: First, the bioavailability of poorly soluble drugs is significantly increased due to the conversion of the drug from the crystalline into its amorphous state [1]. Recent work showed that HME is even capable of converting a liquid nanosuspension into a solid formulation in a one-step process [2], thereby avoiding aggregation of nanocrystals. Second, drug release profiles can be specifically tailored (in most cases retarded release of water soluble drugs) via the application of a proper matrix carrier in combination with plasticisers [3]. Third, drug abuse can be prevented due to superior mechanical properties of the final product [4].
Understanding Continuous High Shear Wet Granulation in Pharmaceutical Production
Written by
Introduction
Continuous processing is a promising approach for solid dosage manufacturing. High-shear wet granulation is performed in continuous mode using twin screw granulators (TSG), characterized by a modular screw profile including a sequence of different screw elements with various shapes, orientation and functions. For process engineers it is a challenge to come up with prediction models to establish the relationship between equipment and material attributes, process data and the end-product testing results. If a reliable model is available which is able to predict the quality of the product, it can be inverted to obtain the design space, corresponding to that set of operating conditions required for achieving the target product quality (Figure 1). Such a modelling framework combined with in-process measurements, can provide a good mechanistic insight into the important parameters of continuous
Introduction
Oral films have gained interest in the last couple of years. Films for oral application offer an interesting new approach for drug administration. Active pharmaceutical ingredients (API) can be implemented in thin-sheeted polymer film matrices. These dosage forms are intended to be placed in mouth to dissolve in the saliva without the need of additional liquid and without swallowing of a solid dosage form.
Experimental and Numerical Analysis of an Active Coating Process
Written by Sarah Just and Gregor Toschkoff
Introduction
The inter-tablet coating uniformity is a critical quality attribute in active coating processes. In this project an active coating process is performed in order to produce a fixed dose combination of a sustained release formulation in the tablet core and an immediate release dose in the coating layer. The tablet cores consist of a push-pull osmotic system containing nifedipine as API (Adalat GITS). They are coated with Candesartan cilexetil as a second API. As the inter-tablet coating uniformity is a critical quality attribute to comply with regulatory requirements, the purpose of this work is to enhance the process understanding and to optimize the coating process with regard to the coating uniformity. Besides experimental investigations, PAT tools such as Raman spectroscopy [1] and terahertz pulsed imaging [2] have been applied to study this active coating process. In recent years, numerical simulations of coating processes have been gaining interest as analytical tool [3]. The discrete element method (DEM) in particular is suitable to simulate the tablet motion [4]. In this project, both experimental and numerical analysis of an active coating process is combined to investigate the influence of different process parameters with respect to the optimization of the coating uniformity.
Magnetic Resonance Imaging
The use of MRI as a powerful imaging and characterization modality in pharmaceutical dissolution research is now well established [1]. The non-invasive and non-destructive nature of MRI enables the investigation of structural, chemical and dynamical processes in many optically opaque systems at the microscopic level. Spatial maps of water penetration, tablet swelling and dissolution, as well as the mobilization and distribution of drug products can now be quantified and visualized [2,3]. In addition, the hydrodynamics within a USP recommended flow-through dissolution apparatus can also be visualized by MRI [4]. Such comprehensive information is essential in pharmaceutical research for: (i) the correct interpretation of conventional drug dissolution profiles and (ii) the optimal design (QbD) of controlled release formulations.
Lipid-based drug delivery systems have become a popular approach for the delivery of poorly water-soluble drugs. The limitations associated with this formulation strategy have been the drug solubility in the delivery systems and the lack of characterization techniques predicting the in vivo performance. Solid state characterization of the in vitro digestion products has provided new insights that scrutinize current paradigms in the development of lipid-based drug delivery systems.
Formulation of co-amorphous drug systems
Using the amorphous form of a drug, instead of its crystalline counterpart is one way to enhance the bioavailability of poorly water-soluble drugs. However, in order to fully benefit from the solubility advantages of amorphous drugs, one needs to overcome phyisco-chemical limitations including poor physical stability associated with the amorphous form. Co-amorphous drug formulations are a novel and one of the most promising formulation approaches in this context, where the drug in its amorphous form is stabilized through strong intermolecular interactions with its co-amorphous low molecular weight partner molecule.
The major challenge during preformulation is to gain the greatest possible knowledge about candidate drug compounds with minimal use of resources. Therefore, rapid approaches are proposed for identifying critical conditions for existence of various solid forms so that sudden appearance of new forms and unpredictable stability issues can be avoided during later stages of product development.
Terahertz Pulsed Imaging
Since 2007 when terahertz pulsed imaging (TPI) was first developed to non-destructively measure the coating thickness of pharmaceutical tablets there has been intense research in the PSSRC into how this technique can help improve the quality of pharmaceutical coatings and thus make controlled release technology based on coatings of single dosage forms attractive to industry.
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