Spray drying robot for high-throughput combinatorial fabrication of multicomponent solid dispersions

During the development of pharmaceutical spray-dried formulations, many samples must be prepared for physico-chemical characterisation and dissolution testing by systematically varying parameters such as drug loading or the grades and ratios of excipients (polymers, surfactants, etc.). When spray drying from organic solvents in a traditional laboratory set-up, the process must be stopped after producing each sample and then re-started, which makes combinatorial exploration of the formulation design space rather time-consuming. The present work reports a new approach using a device built around a commercially available laboratory spray dryer, which enables the preparation of powder samples with systematically varying composition within a single spray drying run.

The device consists of three main parts whose purpose is to achieve: i) automatic combinatorial preparation of feed mixtures from up to 9 different stock solutions; ii) removal of adhered particles from the internal glass walls of the cyclone to minimise sample cross-contamination; and iii) automatic collection of individual powder samples in sealed vials without breaking the inert atmosphere. To validate the device operation and to demonstrate its ability to produce sets of powder samples in a short time, two cases studies were conducted: a model system with ternary mixtures of coloured lactose, and a pharmaceutical co-amorphous formulation with two actives and a polymeric excipient.

The case studies show that an identical set of samples can be produces by up to 8× faster compared to manual screening, while keeping sample cross-contamination at around 1%. Ultimately, this can significantly increase the throughput of data collection and analysis during powder formulation studies.

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Materials

Phosphate buffered saline (PBS) tablets (CN: P4417) and ethanol (p.a.) were purchased from Sigma-Aldrich. Paracetamol, hydrochlorothiazide (CTX Life sciences), valsartan (Jubilant) and lactose monohydrate (Lactochem®) were kindly donated by Zentiva k.s. Printer dyes (cyan, magenta, yellow) were collected from HP CZ112 printer cartridges. Demineralized water was prepared by the Aqual 25 system (conductivity ∼0.27 μS/cm).

Vojtěch Klimša, Gabriela Ruphuy, Jan Jonáš, Lucie Mašková, Ondřej Kašpar, Pavel Žvátora, František Štěpánek,
Spray drying robot for high-throughput combinatorial fabrication of multicomponent solid dispersions,
Powder Technology, Volume 428, 2023, 118872, ISSN 0032-5910, https://doi.org/10.1016/j.powtec.2023.118872.

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