Custom fractional factorial designs to develop atorvastatin self-nanoemulsifying and nanosuspension delivery systems – enhancement of oral bioavailability

Figures & data

Table 1 ATR SNEDDS and NS experimental runs showing factor combinations

Run	Factors
	SNEDDS			NS
	Oil concentration (%)	Surfactant concentration (%)	Co-surfactant concentration (%)	Stabilizer concentration (%)	Homogenization speed (rpm)	Sonication time (seconds)
1	25	55	20	0.1	10,000	30
2	25	55	20	0.1	10,000	300
3	20	70	10	0.1	20,000	30
4	20	60	20	0.1	20,000	300
5	20	50	30	0.5	10,000	30
6	15	75	10	0.5	10,000	300
7	10	80	10	0.5	20,000	30
8	10	60	30	0.5	20,000	300
9	10	20	70	1	10,000	30
10	10	30	60	1	10,000	300
11	10	40	50	1	20,000	30
12	5	75	20	1	20,000	300
13	5	20	75
14	5	90	5

Abbreviations: ATR, atorvastatin; SNEDDS, self-nanoemulsifying drug delivery systems; NS, nanosuspensions.

Figure 1 Ternary phase diagrams of ATR SNEDDS with the composition of various components.

Notes: Shaded yellow area shows formation of clear or slight bluish dispersions with no precipitation of the drug in the nanoemulsion region.
Abbreviations: ATR, atorvastatin; SNEDDS, self-nanoemulsifying drug delivery systems.

Table 2 Observed responses of all formulations of experimental design

Run	SNEDDS			Solid NS
	Y1	Y2	Y3	Y1	Y2	Y3
1	97.7	−26	12	556	−4.61	98.1
2	98.8	−22.7	11	315.1	−6.45	93.5
3	146.6	−25.7	14	451.3	2.07	91.3
4	123.7	−24.15	15	499.5	−6.02	92.9
5	141.6	−23.1	15	434	2.72	97
6	158.5	−21.8	14.2	311.2	4.22	93.5
7	142.3	−17.8	12	247.8	8.00	92.9
8	98.6	−22.3	12.3	461	4.03	96.3
9	163.8	−20	13	334.4	−7.32	88.9
10	151.2	−19.3	11	329.4	−6.31	85.6
11	93.4	−17.6	11.5	269.1	0.6	85.3
12	110.3	−16.5	12	612	3.57	91.4
13	128.5	−11.3	9
14	133.7	−14.6	11

Notes: Y₁ for SNEDDS, mean globule size (nm); Y₂ for SNEDDS, zeta potential (mV); Y₃ for SNEDDS, conductivity (μs/cm); Y₁ for NS, mean particle size (nm); Y₂ for NS, zeta potential (mV); Y₃ for NS, yield (%).

Abbreviations: SNEDDS, self-nanoemulsifying drug delivery systems; NS, nanosuspensions.

Table 3 Analysis of variance (ANOVA) results of multiple regression analysis of the investigated responses

Response model	SNEDDS					NS
	ANOVA for responses Y1–Y3					ANOVA for responses Y1–Y3
	df	Sum of squares	Mean square	F ratio	P-value	df	Sum of squares	Mean square	F ratio	P-value
Y1	5	6,035.8	1,207.2	5.9	0.0143	7	145,524.5	20,789.2	13.6	0.012
Y2	5	207.4	41.5	11	0.002	7	294.7	42.1	9.3	0.024
Y3	5	27.2	5.4	3.9	0.0435	7	180.5	25.8	51.8	0.0009

Notes: Y₁ for SNEDDS, mean globule size (nm); Y₂ for SNEDDS, zeta potential (mV); Y₃ for SNEDDS, conductivity (μs/cm); Y₁ for NS, mean particle size (nm); Y₂ for NS, zeta potential (mV); Y₃ for NS, yield (%).

Abbreviations: df, degrees of freedom; SNEDDS, self-nanoemulsifying drug delivery systems; NS, nanosuspensions.

Table 4 Estimated effects and associated P-values for all three responses

Responses		Factors
		X1	X2	X3	X1.X2	X1.X3	X2.X3
SNEDDS
Y1	Estimated effect	−25.84076	1.263	1.644	0.364	0.415	−0.056
	P-value	0.0085*	0.0016*	0.0035*	0.0082*	0.0055*	0.0026*
Y2	Estimated effect	1.667	−0.085	−0.018	−0.030	−0.033	−0.001
	P-value	0.137	0.0479*	0.748	0.060	0.052	0.484
Y3	Estimated effect	−1.749	0.0817	0.033	0.026	0.029	−0.0002
	P-value	0.0215*	0.0064*	0.3464	0.0156*	0.0116*	0.8470
NS
Y1	Estimated effect	−34.625	22.370	22.108	19.014	65.932	81.166
	P-value	0.0665	0.1189	0.1221	0.2404	0.0088*	0.0020*
Y2	Estimated effect	0.693	2.551	−0.637	1.398	1.726	−0.813
	P-value	0.4091	0.0143	0.3587	0.1362	0.0831	0.2565
Y3	Estimated effect	2.625	0.060	−1.820	1.632	0.341	−1
	P-value	0.0009*	0.8159	0.0017*	0.0053*	0.3145	0.0146*

Note:

* Significant effect of factors on individual responses. Y₁ for SNEDDS, mean globule size (nm); Y₂ for SNEDDS, zeta potential (mV); Y₃ for SNEDDS, conductivity (μs/cm); Y₁ for NS, mean particle size (nm); Y₂ for NS, zeta potential (mV); Y₃ for NS, yield (%).

Abbreviations: SNEDDS, self-nanoemulsifying drug delivery systems; NS, nanosuspensions.

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

Abbreviations: SNEDDS, self-nanoemulsifying drug delivery systems; NS, nanosuspensions.

Figure 3 Standard Pareto charts showing the effects of independent variables and their combined effects on the designed responses of SNEDDS and NS formulations.

Abbreviations: SNEDDS, self-nanoemulsifying drug delivery systems; NS, nanosuspensions.

Figure 4 TEM image of optimized SNEDDS formula (A) and SEM image of optimized NS formula (B).

Abbreviations: TEM, transmission electron microscope; SNEDDS, self-nanoemulsifying drug delivery systems; SEM, scanning electron microscope; NS, nanosuspensions.

Figure 5 In vitro release of optimized SNEDDS and NS formulations.

Abbreviations: SNEDDS, self-nanoemulsifying drug delivery systems; NS, nanosuspensions; ATR, atorvastatin.

Figure 6 Means of plasma concentrations-time profiles and in vivo pharmacokinetic parameters (inset) of optimized ATR SNEDDS and optimized ATR solid NS versus ATR suspension and commercial tablets.

Note: Data represent the mean value ± standard deviation (n=6).
Abbreviations: ATR, atorvastatin; SNEDDS, self-nanoemulsifying drug delivery systems; NS, nanosuspensions; C_max, Maximum plasma level; AUC_[0–], area under curve; hr, hour; K_e, elimination rate constant; T_1/2, half life time; MRT, mean residence time.