Efek komposisi nanopartikel poly (lactic acid) dan poly (lactic-co-glycolic acid) serta penambahan surfaktan kationik didodecyldimethylammonium bromide (DDAB) terhadap rilis dexamethasone berkelanjutan = Effect of the composition of poly (lactic acid) and poly (lactic co glycolic acid) nanoparticles with cationic surfactant didodecyldimethylammonium bromide (DDAB) addition for dexamethasone long term release