Collaborative Study for Analysis of Subvisible Particles Using Flow Imaging and Light Obscuration: Experiences in Japanese Biopharmaceutical Consortium.

The evaluation of subvisible particles, including protein aggregates, in therapeutic protein products has been of great interest for both pharmaceutical manufacturers and regulatory agencies. To date, the flow imaging (FI) method has emerged as a powerful tool instead of light obscuration (LO) due to the fact that (1) protein aggregates contain highly transparent particles and thereby escape detection by LO and (2) FI provides detailed morphological characteristics of subvisible particles. However, the FI method has not yet been standardized nor listed in any compendium. In an attempt to assess the applicability of the standardization of the FI method, we conducted a collaborative study using FI and LO instruments in a Japanese biopharmaceutical consortium. Three types of subvisible particle preparations were shared across 12 laboratories and analyzed for their sizes and counts. The results were compared between the methods (FI and LO), inter-laboratories, and inter-instruments (Micro Flow Imaging and FlowCam). We clarified the marked difference between the detectability of FI and LO when counting highly transparent protein aggregates in the preparations. Although FlowCam provided a relatively higher number of particles compared with MFI, consistent results were obtained using the instrument from the same manufacturer in all 3 samples.

Long-lasting immunosuppressive effects of tacrolimus-loaded micelle NK61060 in preclinical arthritis and colitis models.

AIM: Tacrolimus (TAC) is an important drug for inflammatory diseases. However, TAC has several limitations, such as variable trough concentrations among individuals and a high medication frequency. In this study, we created NK61060, a novel micellar TAC formulation, to circumvent these disadvantages. MATERIALS & METHODS: Immunosuppressive activity of NK61060 was determined in the collagen-induced arthritis rat model, mannan-induced arthritis mouse model and dextran sodium sulfate-induced colitis mouse model. The pharmacokinetics and toxicology of NK61060 were evaluated in those models. RESULTS: In arthritis and colitis models, NK61060 exhibited superior immunosuppressive activity compared with that of TAC. Pharmacokinetic and toxicological analyses indicated that NK61060 had a wider safety margin and could be administered at a reduced medication frequency. CONCLUSION: NK61060 mitigates the trough concentration variability and the medication frequency and it may be a safer and more effective option for use in clinical settings. Further studies are needed to determine its clinical usefulness.