Figure 6 :Scanning electron microphotographs appearance of metformin microballoons (a) Eudragit S100/L100 = 9:1, (b) Eudragit S100/L100-55, (c) Eudragit S100 /HPMCP = 9:1, (d) Eudragit S100/HPMC = 9:1, (e) Eudragit S100/EC = 9:1