Optimized zein nanospheres for improved oral bioavailability of atorvastatin

Figures & data

Table 1 Experimental runs showing combinations of factors

Run	Factors
	X1	X2	X3
1	50	8.75	1.5
2	50	9.25	1.5
3	50	8.75	3
4	50	9.25	3
5	83.3	8.75	1.5
6	83.3	9.25	1.5
7	83.3	8.75	3
8	83.3	9.25	3
9	90.1	8.75	1.5
10	90.1	9.25	1.5
11	90.1	8.75	3
12	90.1	9.25	3

Notes: X₁, weight % of zein to atorvastatin; X₂, pH; X₃, stirring time (hours).

Table 2 Observed responses for 12 formulations of experimental design

Run number	Responses
	Y1	Y2	Y3	Y4	Y5
1	378	17.79	15	7.5	40
2	412	18.2	33.67	67.34	52
3	316	−13.82	17.22	34.44	76
4	395	−14.5	19.72	39.44	88
5	483	−1.92	14.86	29.71	64
6	223	−8.3	17.7	43.33	61.3
7	830	−7.39	12.8	17.6	66.6
8	877	−9.13	12.1	24.14	68.7
9	722	−2.34	9.04	18.08	62.4
10	619	−2.1	14.8	19.5	62
11	1,045	−3.4	12.52	25.04	72.4
12	1,089	−4.5	12.72	25.44	75.3

Abbreviations: Y₁, mean particle size (nm); Y₂, zeta potential (mV); Y₃, drug loading efficiency (%); Y₄, drug encapsulation efficiency (%); Y₅, yield (%).

Table 3 Analysis of variance of multiple regression analysis for the investigated dependent variables

Response model	ANOVA for dependent variables Y1–Y5
	df	Sum of squares	Mean square	F ratio	P-value
Y1	6	825,316.23	137,553	6.6047	0.0280
Y2	6	1,146.5905	191.098	13.1972	0.0062
Y3	6	394.61791	65.7697	8.9970	0.0145
Y4	6	1,935.4322	322.572	2.2046	0.2017
Y5	6	1,550.8723	258.479	13.6949	0.0057

Notes: Y₁, mean particle size (nm); Y₂, zeta potential (mV); Y₃, drug loading efficiency (%); Y₄, drug encapsulation efficiency (%); Y₅, yield (%).

Abbreviation: ANOVA, analysis of variance; df, degrees of freedom.

Table 4 Estimated effects and associated P-values for all five dependent variables

Dependent variables		Factor
		X1	X2	X3	X1X2	X1X3	X2X3
Y1	Estimated effect	542,497,837	−39,595.45	180,963,768	445,176,611	−13,406.9	494.72416
	P-value	0.3630	0.5589	0.3629	0.3676	0.5532	0.0480*
Y2	Estimated effect	2,432,924.9	−509.9535	814,005.24	1,981,473.2	−182.7979	31.673902
	P-value	0.8715	0.7722	0.8711	0.8738	0.7558	0.0015*
Y3	Estimated effect	26,709,931	−2,918.294	−8,908,207	−22,676,528	−975.4479	5.3025948
	P-value	0.047*	0.057	0.0466*	0.0432*	0.0567	0.1964
Y4	Estimated effect	66,168,786	−9,987.112	−22,069,457	−56,612,169	−3,330.671	−0.782373
	P-value	0.2052	0.1184	0.2052	0.1934	0.1184	0.9627
Y5	Estimated effect	9,576,282.7	−4,013.15	3,191,485.5	7,291,855.7	−1,327.189	−28.2089
	P-value	0.5829	0.0890	0.5832	0.6132	0.0910	0.0043*

Notes:

* Significant effect of factors on individual dependent variables. Y₁, mean particle size (nm); Y₂, zeta potential (mV); Y₃, drug loading efficiency (%); Y₄, drug encapsulation efficiency (%); Y₅, yield (%); X₁, weight % of zein to atorvastatin; X₂, pH; X₃, stirring time (hours).

Figure 1 Three-dimensional response surface plots showing the effect of the study factors on the dependent variables.

Figure 2 Quantile–quantile plots for predicting the dependent variables.

Abbreviations: RMSE, root-mean-square error.

Figure 3 Standard Pareto charts showing the effects of independent variables and their combined effects on mean particle size, zeta potential, drug loading efficiency, drug encapsulation efficiency, and yield.

Figure 4 Scanning electron micrograph of optimized atorvastatin–zein formulation.

Figure 5 X-ray diffraction patterns of raw atorvastatin and optimized atorvastatin– zein nanospheres.

Abbreviation: ATR, atorvastatin.

Figure 6 In vitro diffusion of optimized atorvastatin–zein nanospheres.

Abbreviation: ATR, atorvastatin.

Figure 7 Means of plasma concentration-time profiles and in vivo pharmacokinetic parameters (inset) for optimized atorvastatin–zein nanospheres versus atorvastatin suspension and the commercially available tablets after a 25 mg/kg oral dose of atorvastatin.

Abbreviations: AUC, area under the concentration time curve; ATR, atorvastatin; MRT, mean residence time.