Experimental Design Approach in Erythropoietin‑alginate Microsphere Preparation with Different Concentrations of Drug and Polymer

Background: Microspheres as drug delivery system has been selected to increase stability of Erythropoietin (EPO) to achieve efficacy. Aim: Aim of this research was to determine effect of polymer and EPO concentrations on the characteristics. Materials and Method: Microspheres involved sodium alginate as polymer and CaCl2 as a crosslinker. The concentrations of sodium alginate used were 2% and 3%, and  EPO were 5000 IU and 10000 IU. Formula of microspheres which consist of 2% and 3% of alginate and 5000  IU  EPO  were  called  F1  and  F2  respectively,  whereas  microspheres  using  2  and  3%  alginate  and  10000 IU EPO was named F3 and F4 respectively. Characterization including morphology, particle size, swelling index, and yield of microspheres prepared by ionotropic gelation aerosolization technique. Design of  Experiment  (DoE)  was  used  to  analyze  the  formula.  Results: Results showed that particle sizes of EPO‑alginate microspheres were 3.36 ± 0.126µm, 3.42 ± 0.098µm, 3.88 ± 0.131µm and 3.95 ± 0.151µm for F1, F2, F3 and F4 respectively. The swelling index measurement based on mass and particle size of microspheres  of  all  formulas  showed  an  index  of  less  than  10.  Respectively,  yield  was  77.84  ±  0.290%,  86.65 ± 0.191%, 91.89 ± 0.210%, and 94.65 ± 0.252% for F1 to F4. Using the ANOVA factorial design, it  was  found  that  increasing  sodium  alginate  concentration  significantly  increased  yield,  while  increasing  EPO concentration significantly increased particle size and yield of microspheres. Both sodium alginate and EPO concentrations did not affect swelling index of microspheres. Range concentrations of sodium alginate and EPO that produced optimal characteristics of microspheres can be observed in the feasible area of design space overlaid contour plot generated from DoE study. Conclusion: EPO-alginate microspheres demonstrated the prospective as carrier and DoE is potential for further optimized formulations.