Search

Purpose: To make a comparative study on sustained delivery performance of rhIFN with random amorphous and spherical crystal-like ordered self-assemblies., Methods: The rhIFN self-assemblies were identified in batch crystallization mode. Physico-chemical characteristics were compared, including morphology, XRD, FTIR, CD, biological potency, the dissolution behaviors in vitro and plasma pharmacokinetics in vivo. Moreover, molecular simulation was performed to better understand their binding site and mode., Results: Here, we suggest that random amorphous and spherical ordered self-assemblies allow for long action without new molecular entities generation or carriers employed. By manipulating supersaturation, the ordered aggregates were self-organized at high concentration of Zn(II) (>100 mM) in pH 5.5-6.0, which was the first time that spherical semi-crystals of rhIFN can act as a depot source for the sustained delivery of biologically active proteins. The secondary structure and biological potency of rhIFN were unchanged after aggregation. Compared with that of the native rhIFN, both self-assemblies exhibited slower absorption and extended elimination profiles after s.c. administration, which were characterized as 4.75 ± 0.82 h and 10.58 ± 1.86 h of terminal half-life for random amorphous and spherical ordered self-assemblies, respectively., Conclusions: The work described here demonstrates the possibility of self-assemblies of biomacromolecules for controllable release application of therapeutic proteins.

This study develops protein spherulite, a new form of protein aggregation, for sustained-release applications of recombinant human interferon α-2b (rhIFN). rhIFN spherulites were prepared with different pH solutions with different kinds and concentrations of zinc salts at various incubation temperatures. rhIFN spherulites produced under different systems were of different morphology properties and in vitro release characters. Size-exclusion high-performance liquid chromatography analysis has shown that no protein aggregates were generated during spherulite formation, and cytopathic inhibition assay has demonstrated that the spherulitic rhIFN well maintained its structure and antiviral activity. In vivo studies showed that rhIFN spherulites provided a significantly prolonged pharmacokinetics profile profile as compared with the soluble rhIFN formulation, and the relative bioavailability based on serum rhIFN levels was about 170%. The work described here demonstrates the possibility of protein spherulites as a long-acting formulation for rhIFN., (Copyright © 2010 Wiley-Liss, Inc.)

This study focuses on extending the release period of zinc-protein chelate through protamine modification. Recombinant human interferon-α-2b (rhIFN), a highly pleiotropic cytokine with a short intrinsic pharmacokinetic half-life when injected subcutaneously (∼2-6 h), was used as a model drug. Protamine modified zinc-rhIFN chelate microparticles were prepared by co-precipitating rhIFN with zinc and protamine. Introduction of protamine (2.5-20 mg/mL) into the chelation system had several prominent effects. First, percentage of chelated rhIFN was lowered (from >99% to ∼90%); second, particle size was gradually increased (from ∼0.45 μm to ∼2 μm); last but important, it extended the release period of the chelate both in vitro (complete release was retarded from 8 h to 48 h) and in vivo (t(1/2) was prolonged from 4.5 h to 15.5 h and mean residence time from 9.4 h to 29.6 h). Size-exclusion liquid chromatography and cytopathic effect inhibition assay indicated rhIFN preserved its structural and functional integrity in these chelates., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Objective: This study presents a preliminary exploration on extending the half-life of therapeutic proteins by crystallization strategy without new molecular entities generation., Methods: Recombinant human interferon (rhIFN) α-2b, a model protein drug in this case, was crystallized using a hanging-drop vapor diffusion method. A novel chelating technique with metal ions was employed to promote crystals formation., Results: The effects of key factors such as seeding protein concentration, pH of the hanging drop, ionic strength of the equilibration solution, and precipitants were investigated. Size-exclusion liquid chromatography, antiviral activity determination, and enzyme-linked immunosorbent assay indicated that both the molecular integrity and biological potency of rhIFN were not significantly affected by crystallization process. In addition, the in vitro release behavior of rhIFN from crystal lattice was characterized by an initial fast release, followed by a sustained release up to 48 hour., Conclusion: The work described here suggested an exciting possibility of therapeutic protein crystals as a long-acting formulation.