Table 2.

Variables and observed responses in the CCD for the microemulsion

	Independent variables		Dependent variables		Viscosity (mPa · s)	Particle size (nm)	Polydispersity index
	X1	X2	Y1(Q24)	Y2(Jss)
ME1	0.65	0.119	58.22	3.3735	33±1.56	15.6±1.20	0.101±0.0023
ME2	0.65	0.225	132.91	6.3521	37±2.38	23.1±0.89	0.114±0.0051
ME3	0.509	0.225	91.21	4.2839	254±5.21	21.5±0.97	0.197±0.0039
ME4	0.75	0.3	80.32	3.7427	15±1.67	36.8±0.44	0.125±0.0060
ME5	0.75	0.15	49.43	2.8226	22±3.33	18.9±1.34	0.089±0.0031
ME6	0.65	0.225	129.19	6.2363	37±2.38	23.1±1.09	0.114±0.0051
ME7	0.55	0.3	89.23	4.1527	159±5.23	46.6±2.08	0.218±0.0012
ME8	0.791	0.225	68.86	3.2545	18±2.33	24.2±2.12	0.096±0.0027
ME9	0.65	0.225	131.88	6.3788	37±2.38	23.1±0.89	0.114±0.0051
ME10	0.65	0.225	127.65	6.2436	37±2.38	23.1±0.89	0.114±0.0051
ME11	0.65	0.331	103	3.9042	25±3.89	65.4±2.29	0.144±0.0042
ME12	0.55	0.15	60.4	3.4354	226±5.76	16.2±0.84	0.128±0.0045
ME13	0.65	0.225	135.43	6.5222	37±2.38	23.1±0.89	0.114±0.0051
Independent variables			Levels used, actual (coded)
			−1	0	+1	−alpha	+alpha
X1 = water/microemulsion (w/w)			0.55	0.65	0.75	0.509	0.791
X2 = oil/Smix (w/w)			0.15	0.225	0.3	0.119	0.331

Note: Each data represents the mean ± SD (n=3).

Abbreviations: CCD, Central composite design; J_ss, steady-state flux; ME, microemulsion formulation; Q₂₄, permeation of rotigotine in 24 hours; SD, standard deviation.