Objectives: Microcomputed tomography (µCT) is a powerful analytical tool for non-invasive structural analysis. The stability of drug substances and formulations subjected to X-ray radiation may be a concern in the industry. This study examines the effect of X-ray radiation on the stability of freeze-dried pharmaceuticals. The investigation is a proof of concept study for the safety of µCT X-ray radiation doses during the non-destructive investigation of freeze-dried products.
Methods: Different formulations of clotrimazole, insulin and l-lactate dehydrogenase were freeze-dried and the products exposed to a defined dose of radiation by µCT. Conservative freeze-drying conditions were used. Irradiated and normal samples were analysed for their stability directly after freeze-drying and after stability testing.
Key findings: The stability of model compounds was well maintained during freeze-drying. Some degradation of all compounds occurred during accelerated stability testing. The results showed no differences between the irradiated and normal state directly after freeze-drying and accelerated stability testing.
Conclusions: No evidence of a detrimental effect of 100 Gy X-ray exposure on a model small molecule, peptide and protein compound was found while useful structural information could be obtained. Consequently, the technology may be useful as a non-destructive tool for product inspections if the formulation proves stable.
Keywords: freeze-drying; inspection; micro computed tomography; morphology; stability.
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