Novel Cleaning-in-Place Strategies for Pharmaceutical Hot Melt Extrusion

Tailoring the release of highly loaded amorphous solid dispersions via additive manufacturing

In the last decades, tremendous improvements have been made in enhancing the bioavailability of poorly soluble active pharmaceutical ingredients (APIs). Lately, their customisation potential has become a reality through filament-based 3D-printing (3DP). Highly loaded oral amorphous solid dispersions (ASDs) are of particular interest, since they drastically reduce the pill burden. However, such systems are limited by their high tendency of API recrystallisation, compromising the API solubility and the mechanical properties of filaments fabricated for 3DP. The following work closes this gap by developing compact 3DP tablets containing an ASD system of 70 % itraconazole in hydroxypropyl methylcellulose acetate succinate (HPMCAS). The processability via HME and 3DP processes was thoroughly investigated by considering filament properties such as solid-state, rheology and mechanical behaviour. Even after six months of storage, the ASD did not show recrystallisation and maintained a zero-order drug release for variable 3DP infill patterns, demonstrating the potential of this approach for on-demand processing at the point-of-care. A strong differentiation in release kinetics was found for different infills that can be used for further improvement of the product to allow tailored release rates. This work provides a strong basis for successful personalisation of highly loaded ASDs via 3DP.

Experimental design of a film flow cleaning rig equipped with in-line process analytical technology (PAT) tool for real-time monitoring

The main purpose of this research was to develop an experimental film flow cleaning rig that can be combined with Process analytical technology (PAT) tools to reduce cleaning time and costs. Here, we show that the use of in-line UV-Vis was successful for real-time monitoring of the cleaning process of olanzapine as a challenging residue to clean. The cleaning process was found to be affected by the properties of the olanzapine soil, and the study showed the competing effects of mechanical lift-off and dissolution action with methanol as a solvent. However, The method is limited by the cleaning mechanisms, with the dissolution being the only mechanism that can be accurately quantified using an in-line UV-Vis PAT tool. This experimental approach can be used to optimize cleaning process conditions and solvent choices at the bench scale before deployment. The material of which the cleaning rig was printed limited the solvent that could be used for this study, and future modifications will include a more chemical-resistant material.

Pharmaceutical hot melt extrusion process development using QbD and digital twins

Pharmaceutical product development guided by Quality by Design (QbD) is based on a complete understanding of the critical process parameters (CPPs) that are important for achieving the desired product critical quality attributes (CQAs). The effect of process settings, such as the screw speed, the throughput, the barrel temperature, and the screw configuration, is a well-known factor in the setup of pharmaceutical hot melt extrusion (HME) processes. A CPP that has not yet been extensively researched is the type of cross-section geometry of the screw elements. Typically, pharmaceutical extruders have double-flighted screw cross-sections, with some elements having a single- or triple-flighted element section. The exception is a NANO16 extruder from Leistritz, with all screw elements having a triple-flighted screw geometry. We investigated the process setup and scale-up to a double-flighted extruder experimentally and in silico via a digital twin. Two formulations were processed on a NANO16 extruder and virtually transferred to a ZSE18 double-flighted co-rotating twin-screw extruder. Detailed smoothed particle hydrodynamics simulations of all screw elements available from both extruders were performed, and their efficiency in conveying, pressure build-up, and power consumption were studied. Reduced-order 1D HME simulations, which were carried out to investigate the process space and scalability of both extruders, were experimentally validated.

In-line monitoring of solid dispersion preparation in small scale extrusion based on UV-vis spectroscopy

The poor solubility of a large number of active pharmaceutical ingredients (APIs) is a major challenge in pharmaceutical research. Therefore, the extrusion of amorphous solid dispersions (ASDs) is one promising approach to enhance the dissolution rate by molecularly dissolving the API in an amorphous carrier polymer. During ASD extrusion, crucial parameters as the dissolution of the API in the carrier polymer need to be monitored. Within this study, a small scale twin screw extruder was coupled with special ColVisTec UV-vis probes that are characterized by their small dimensions. This setup enables a systematic formulation design and optimization based on in-line monitoring of drug dissolution using small material quantities. In fact, sample quantities of about 5 mg were evaluated for each measurement, representing 50% of the material inside the die. The amount of undissolved drug particles was determined based on the lightness of the extrudates. It was shown that the temperature has a significant effect on the drug dissolution in the polymer. Furthermore, complete drug dissolution was shifted to lower temperatures if higher residence times were applied. Based on the courses of lightness, regime maps were modeled that specify the process conditions where ASDs are successfully manufactured.

Quality of FDM 3D Printed Medicines for Pediatrics: Considerations for Formulation Development, Filament Extrusion, Printing Process and Printer Design

3d printing is capable of providing dose individualization for pediatric medicines and translating the precision medicine approach into practical application. In pediatrics, dose individualization and preparation of small dosage forms is a requirement for successful therapy, which is frequently not possible due to the lack of suitable dosage forms. For precision medicine, individual characteristics of patients are considered for the selection of the best possible API in the most suitable dose with the most effective release profile to improve therapeutic outcome. 3d printing is inherently suitable for manufacturing of individualized medicines with varying dosages, sizes, release profiles and drug combinations in small batch sizes, which cannot be manufactured with traditional technologies. However, understanding of critical quality attributes and process parameters still needs to be significantly improved for this new technology. To ensure health and safety of patients, cleaning and process validation needs to be established. Additionally, adequate analytical methods for the in-process control of intermediates, regarding their printability as well as control of the final 3d printed tablets considering any risk of this new technology will be required. The PolyPrint consortium is actively working on developing novel polymers for fused deposition modeling (FDM) 3d printing, filament formulation and manufacturing development as well as optimization of the printing process, and the design of a GMP-capable FDM 3d printer. In this manuscript, the consortium shares its views on quality aspects and measures for 3d printing from drug-loaded filaments, including formulation development, the printing process, and the printed dosage forms. Additionally, engineering approaches for quality assurance during the printing process and for the final dosage form will be presented together with considerations for a GMP-capable printer design.

Novel polyester-based thermoplastic elastomers for 3D-printed long-acting drug delivery applications

To improve patient compliance and personalised drug delivery, long-acting drug delivery devices (LADDDs), such as implants and inserts, greatly benefit from a customisation in their shape through the emerging 3D-printing technology, since their production usually follows a one-size-fits-most approach. The use of 3D-printing for LADDDs, however, is mainly limited by the shortage of flawlessly 3D-printable, yet biocompatible materials. The present study tackles this issue by introducing a novel, non-biodegradable material, namely a polyester-based thermoplastic elastomer (TPC) - a multi-block copolymer containing alternating semi-crystalline polybutylene terephthalate hard segments and poly-ether-terephthalate amorphous soft segments. Next to a detailed description of the material's 3D-printability by mechanical, rheological and thermal analyses, which was found to be superior to that of conventional polymers (ethylene-vinyl acetates (EVA)), this study establishes the fundamental understandings of the interactions between progesterone (P4) and TPC and drug-releasing properties of TPC for the first time. P4-loaded LADDDs based on TPC, prepared via an elaborated solvent-immersion technique, enable the release of P4 at pharmacologically relevant rates, similar to those of marketed formulations based on EVA and silicones. Additionally, TPC demonstrated an exceptional 3D-printability for a wide selection of implant sizes and complex geometries.