Optimising 3D printed medications for rare diseases: In-line mass uniformity testing in direct powder extrusion 3D printing
Abstract
Biotinidase deficiency is a rare inherited disorder characterized by biotin metabolism issues, leading to neurological and cutaneous symptoms that can be alleviated through biotin administration. Three-dimensional (3D) printing (3DP) offers potential for personalized medicine production for rare diseases, due to its flexibility in designing dosage forms and controlling release profiles. For such point-of-care applications, rigorous quality control (QC) measures are essential to ensure precise dosing, optimal performance, and product safety, especially for low personalized doses in preclinical and clinical studies. In this work, we addressed QC challenges by integrating a precision balance into a direct powder extrusion pharmaceutical 3D printer (M3DIMAKER™) for real-time, in-line mass uniformity testing, a critical quality control step. Small and large capsule-shaped biotin printlets (3D printed tablets) for immediate- and extended-release were printed. The integrated balance monitored and registered each printlet’s weight, identifying any deviations from acceptable limits. While all large printlet batches met mass uniformity criteria, some small printlet batches exhibited weight deviations. In vitro release studies showed large immediate-release printlets releasing 82% of biotin within 45 min, compared to 100% for small immediate-release printlets. For extended-release formulations, 35% of the drug was released from small printlets, whereas 24% was released from large printlets at the same time point. The integration of process analytical technology tools in 3DP shows promise in enhancing QC and scalability of personalized dosing at the point-of-care, demonstrating successful integration of a balance into a direct powder extrusion 3D printer for in-line mass uniformity testing across different sizes of capsule-shaped printlets.
Introduction
Biotinidase deficiency is an inherited rare disease characterized by an autosomal recessive disorder of biotin metabolism (Yılmaz, 2024). With a prevalence of 1 in 60,000, untreated patients with biotinidase deficiency may present with neurological and/or cutaneous symptoms, including developmental delay, seizures, hypotonia, sensorineural hearing loss, optic atrophy, alopecia, and skin rashes (Tankeu, 2023, Cowan et al., 2010, Canda et al., 2020). Fortunately, these clinical features can be improved or prevented by administering personalized doses of the water-soluble vitamin biotin. Treatment is tailored to the patient’s metabolic activity and therefore requires continuous adjustments: oral biotin doses of 5–10 mg/day for those with <10 % of average normal serum enzyme activity, and 2.5–10 mg/day for those with 10 % − 30 % of average normal enzyme activity (Tankeu, 2023, Canda et al., 2020, Sayegh, 2020).
Three-dimensional (3D) printing (3DP) is an innovative technology that combines computer-aided design and manufacturing to create an object through successive layers of material (Milliken, 2024, Cardoso and E.s., 2024). Being able to create objects with complex structures and geometries, this technique is well suited to meet the needs of developing personalized dosing for various patient groups, including paediatrics and geriatrics, polypharmacy patients, and individuals with rare diseases (Patel, 2024, Huanbutta, 2023, Fastø, 2019, Januskaite, 2020, Carou-Senra, 2023, Mazarura et al., 2022, Ahola, 2024, Funk, 2024). 3DP allows for the flexible production of small batches with customisations in dose, shape, drug release kinetics, composition, and the incorporation of multiple drugs into a single dosage form (Boniatti, 2021, Mora-Castaño et al., 2023, Shojaie et al., 2023, Muhindo, 2023, Denis, 2024, Windolf, 2022). Pharmaceutical 3DP has already shown advantages over conventional formulations in the production of personalized medicines for bioequivalence (Lyousoufi, 2023) and clinical studies targeting specific populations and rare diseases (Goyanes, 2019a, Goyanes, 2019b, Rodríguez-Pombo, 2024a, Rodríguez-Pombo, 2024b, Liu, 2023)
Among the various 3DP technologies, material extrusion is the most commonly used in the pharmaceutical sector, which includes semisolid extrusion (SSE), fused deposition modelling (FDM), and direct powder extrusion (DPE), depending on the type of drug-loaded ink (pharma-ink) used (Algahtani et al., 2018). SSE 3DP, which employs a gel or paste as the pharma-ink and operates at low temperatures, has been investigated extensively in bioprinting, personalized medicine, and novel dosage forms, such as chewable printlets (Carou-Senra, 2023, Wang, 2023a, Wang, 2023b, Awad, 2023a, Awad, 2023b, Chatzitaki, 2023, Utomo, 2023). Additionally, the use of disposable pre-filled syringes makes SSE closer to meeting the quality control (QC) requirements mandated by regulatory bodies (Vithani, 2019).
FDM, in contrast, uses a drug-loaded thermoplastic filament as the pharma-ink, requiring a hot melt extruder (HME) for filament manufacture (Ghanizadeh Tabriz, 2023). However, this two-step thermal process can degrade the active pharmaceutical ingredient (API) and increase manufacturing time. The need for filaments with specific rheological and mechanical properties further limits its broader application. Therefore, it is necessary to evaluate the stability, quality, and behaviour of the filaments used in this technique (Bandari, 2021, Mora-Castaño, 2022, Oladeji, 2022, Xu, 2020, Okwuosa, 2021, Ayyoubi, 2023, Yang, 2023).
DPE has emerged as an alternative to FDM, by directly printing powder or granulate blends as pharma-inks without filament preparation (Zheng, 2021, Aguilar-de-Leyva, 2023). The powder blend is fed directly into a hopper, transported to a heated nozzle by a single screw, and extruded in a layer-by-layer manner (Goyanes, 2019a, Goyanes, 2019b). This process overcomes some limitations associated with FDM, as it allows for single-step production, reducing thermal stress, and is more efficient due to the small quantity of raw materials needed (Goyanes, 2019a, Goyanes, 2019b, Rosch, 2023, Fanous, 2020). DPE also enables the formation of amorphous solid dispersions (ASDs) with high drug loading, known to enhance drug solubility (Boniatti, 2021, Goyanes, 2019a, Goyanes, 2019b, Wang, 2023a, Wang, 2023b, Pistone, 2023, Mora-Castaño, 2024). Despite its advantages, DPE presents its own challenges in the production of pharmaceutical dosage forms, such as the influence of powder flow, rheological properties, and electrostatic forces. Poor powder can hinder continuous and homogeneous material feed through the screw, causing variability in dosing and limiting the uniformity of weight and API content in the final product (Boniatti, 2021, Rosch, 2023, Pistone, 2023).
The implementation of 3DP in pharmaceuticals must address challenges related to Good Manufacturing Practice (GMP), and the quality of 3D printed products must be guaranteed through rigorous QC measures for optimal performance and safety (Muhindo, 2023, Rosch, 2023, Bendicho-Lavilla, 2024). Mass uniformity testing during the printing process is essential for evaluating reproducibility and ensuring accurate dosing in each pharmaceutical form, a crucial point in the QC of 3DP (Rosch, 2023, Deon, 2022). This becomes particularly important in the case of low personalized doses for rare diseases, where treatment customization and preclinical and clinical studies demand accurate weight determination to ensure efficacy and safety (Díaz-Torres, 2023, Johannesson, 2023). Process analytical technology (PAT) tools offer a solution for ensuring batch-wide mass uniformity and can be installed in-line, at-line, off-line, or on-line (Seoane-Viaño, 2023). For example, a previous study integrated a balance into an SSE pharmaceutical 3D printer, for non-destructive and in-line weight uniformity testing of hydrocortisone printlets (Bendicho-Lavilla, 2024).
The aim of this work was to implement, for the first time, a balance on a multi-printhead 3D printer to monitor the weight and reproducibility of medicine manufactured by DPE 3DP. Two different excipients (polyethylene oxide 100,000 and hydroxypropyl cellulose) were selected to manufacture capsule-shaped printlets for immediate- and extended-release systems, respectively. Two printlet batch sizes, containing 2.5 and 10 mg of biotin, were manufactured for potential use in clinical and preclinical studies using the healthcare M3DIMAKER™ Studio software, which controlled both the 3D pharmaceutical printer and the in-line mass uniformity testing. Finally, physicochemical characterization techniques were used to evaluate the properties of the developed capsule-shaped printlets, assessing biotin content and release profiles for the different printlets.
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Materials
Biotin (MW 244.31 g/mol, Acofarma, Barcelona, Spain) was used as the model drug. Polyethylene oxide 100,000 (PEO, 100,000 Da, Sigma-Aldrich, St. Louis, USA) and hydroxypropyl cellulose (HPC Klucel ELF, 40,000 Da, Ashland, Wilmington, USA) were the selected polymers to manufacture the pharma-inks. Pearlitol flash-mannitol (Roquette, Lestrem, France) was added to the immediate-release pharma-ink to improve printlet resolution and dissolution.
Hydrochloric acid (37 %, Ph. Eur, Scharlau, Barcelona, Spain), sodium phosphate tribasic dodecahydrate (≥98.0 %, Honeywell Fluka, Buchs, Switzerland), sodium hydroxide (Ph. Eur. pellets, VWR International, Radnor, Pennsylvania, USA), and phosphate buffer solution (pH = 3.9) were used for the preparation of the dissolution testing media. Acetonitrile (≥99.9 % v/v, HPLC grade, Merck, Darmstadt, Germany) and trifluoracetic acid (≥99.0 % v/v, HPLC grade, Fisher Scientific, Hampton, USA) were used as the mobile phase for the drug content assay. All materials were used as received.
Gloria Mora-Castaño, Lucía Rodríguez-Pombo, Paola Carou-Senra, Patricija Januskaite, Carlos Rial, Carlos Bendicho-Lavilla, Maria L. Couce, Mónica Millán-Jiménez, Isidoro Caraballo, Abdul W. Basit, Carmen Alvarez-Lorenzo, Alvaro Goyanes, Optimising 3D printed medications for rare diseases: In-line mass uniformity testing in direct powder extrusion 3D printing, International Journal of Pharmaceutics, 2024, 124964, ISSN 0378-5173, https://doi.org/10.1016/j.ijpharm.2024.124964.
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