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.