Table 1.

Variables in the central composite design.

Real Independent Variables	Coded Independent Variable Levels
	Corner Points		Centre Point	Star Points
	–1.414	–1.0	0	+1.0	+1.414
X1 = kafirin (mg)	37.87	100	250	400	462.13
X2 = prednisolone (mg)	48.25	100	225	350	401.75
Real dependent variables		-
Y1 = prednisolone loading (%)		$\frac{\mathrm{amount}\mathrm{of}\mathrm{prednisolone}\left(\mathrm{mg}\right)\mathrm{in}\mathrm{microparticles}}{\mathrm{amount}\mathrm{of}\mathrm{microparticles}\left(\mathrm{mg}\right)}\text{×}100$
Y2 = loading efficiency (%)		$\frac{\mathrm{amount}\mathrm{of}\mathrm{prednisolone}\left(\mathrm{mg}\right)\mathrm{in}\mathrm{microparticles}}{\mathrm{amount}\mathrm{of}\mathrm{prednisolone}\left(\mathrm{mg}\right)\mathrm{initially}\mathrm{added}}\text{×}100$