Surface-tailoring of emulsomes for boosting brain delivery of vinpocetine via intranasal route: in vitro optimization and in vivo pharmacokinetic assessment

Figures & data

Table 1. Combination of independent variables in VNP emulsomes experimental runs prepared according to 3²2¹ full factorial design and their corresponding responses.

Run	PL:SL (X1)	PL:CH (X2)	SL type (X3)	VS (nm) ± SD*	ZP (mV) ± SD*	EE (%) ± SD**	RE24h (%) ± SD**
E1	1:1	2:1	TP	149.95 ± 5.59	–33.88 ± 5.20	71.70 ± 3.82	25.60 ± 2.30
E2	2:1	2:1	TP	254.80 ± 0.28	–42.54 ± 3.45	76.00 ± 5.66	29.71 ± 1.83
E3	3:1	2:1	TP	258.30 ± 3.11	–51.74 ± 3.73	78.60 ± 1.98	38.80 ± 2.32
E4	1:1	4:1	TP	376.50 ± 3.54	–42.60 ± 4.53	74.80 ± 1.13	35.11 ± 2.81
E5	2:1	4:1	TP	284.75 ± 3.89	–61.12 ± 2.01	77.00 ± 1.41	42.90 ± 3.91
E6	3:1	4:1	TP	450.00 ± 1.40	–66.00 ± 5.66	80.70 ± 2.40	46.63 ± 4.84
E7	1:1	8:1	TP	333.00 ± 4.24	–54.00 ± 5.93	76.00 ± 4.24	42.62 ± 4.40
E8	2:1	8:1	TP	349.00 ± 1.41	–63.92 ± 2.16	78.50 ± 3.54	50.01 ± 3.12
E9	3:1	8:1	TP	368.00 ± 4.24	–71.92 ± 3.99	82.00 ± 4.24	54.73 ± 8.71
E10	1:1	2:1	TS	156.70 ± 2.55	–42.21 ± 3.27	72.40 ± 2.26	21.00 ± 4.01
E11	2:1	2:1	TS	318.01 ± 4.95	–44.00 ± 4.95	74.00 ± 5.94	24.02 ± 4.41
E12	3:1	2:1	TS	329.50 ± 3.54	–48.50 ± 4.95	78.00 ± 2.83	25.62 ± 2.15
E13	1:1	4:1	TS	532.52 ± 3.54	–46.00 ± 4.53	75.00 ± 3.25	28.23 ± 2.91
E14	2:1	4:1	TS	554.54 ± 2.12	–64.00 ± 1.90	76.00 ± 3.25	29.83 ± 3.40
E15	3:1	4:1	TS	676.11 ± 4.24	–61.00 ± 2.26	79.50 ± 1.13	34.20 ± 4.61
E16	1:1	8:1	TS	824.53 ± 0.71	–58.01 ± 3.78	76.80 ± 1.84	46.24 ± 5.61
E17	2:1	8:1	TS	857.20 ± 4.24	–72.03 ± 2.83	79.40 ± 5.80	47.00 ± 5.63
E18	3:1	8:1	TS	952.31 ± 2.83	–78.01 ± 2.83	83.00 ± 3.11	49.70 ± 6.61
E19	3:1	2:1	TS	433.83 ± 24.28	11.83 ± 1.76	79.50 ± 6.76	22.84 ± 3.74
E20	3:1	2:1	TS	484.00 ± 43.69	13.00 ± 1.00	83.33 ± 11.31	29.33 ± 3.80
E21	3:1	2:1	TS	521.00 ± 24.26	14.40 ± 2.05	75.59 ± 4.91	30.64 ± 1.60
E22	3:1	2:1	TS	194.67 ± 27.21	–30.30 ± 2.46	81.39 ± 1.86	19.45 ± 1.64
E23	3:1	2:1	TS	202.00 ± 22.69	–22.20 ± 2.71	88.45 ± 6.09	18.18 ± 1.75
E24	3:1	2:1	TS	229.00 ± 15.77	–17.80 ± 2.99	93.45 ± 3.11	14.75 ± 3.69

Abbreviations: SD: Standard deviation; VNP: vinpocetine; PL:SL: phospholipid:solid lipid weight ratio; PL:CH: phospholipid:cholesterol molar ratio; SL: solid lipid; TP: tripalmitin; TS: tristearin; VS: vesicle size; ZP: zeta potential; EE%: entrapment efficiency %; RE_24h: release efficiency after 24 h. E12 = optimized VNP emulsomes; E19-E21 = stearylamine surface-tailored emulsomes, E19 = 0.25 M; E20 = 0.5 M; E21 = 0.75 M; E22-E24 = MPEG-DSPE surface-tailored emulsomes, E22 = 0.1 M; E23 = 0.2 M; E24 = 0.3 M. Results are presented as mean ± SD, *n = 5, **n = 3.

Table 2. Model fit statistics for the responses of VNP emulsomes prepared according to 3²2¹ full factorial design.

Response	Model	p-value	R ^2	Adjusted R ^2	Predicted R ^2	Adequate precision	PRESS	Significant factors and interactions
Y1 : VS (nm)	2FI	.0001	0.9979	0.9910	0.9569	39.170	41932.77	X1, X2, X3, X1X2, X2X3
Y2 : ZP (mV)	Linear	<.0001	0.9317	0.9032	0.8463	18.831	405.18	X1, X2
Y3 : EE (%)	Linear	<.0001	0.9635	0.9483	0.9178	25.039	13.31	X1, X2
Y4 : RE24h %	2FI	.0006	0.9949	0.9785	0.8976	24.557	191.22	X1, X2, X3, X1X3, X2X3

VNP: vinpocetine; VS: vesicle size; ZP: zeta potential; EE%: entrapment efficiency %; RE_24h: release efficiency after 24 h; 2FI: two-factor interaction; PRESS: predicted residual sum of squares.

Figure 1. Response 3D surface plot for the influence of PL:SL weight ratio (X₁), PL:CH molar ratio (X₂), and SL type (X₃) on VS (Y₁) of VNP emulsomes. (A) SL type (Tripalmitin), (B) SL type (Tristearin), (C) PL:CH (4:1), and (D) PL:SL (2:1).

Figure 2. Response 3D surface plot for the influence of PL:SL weight ratio (X₁), PL:CH molar ratio (X₂), and SL type (X₃) on ZP (Y₂) of VNP emulsomes. (A) SL type (Tripalmitin), (B) SL type (Tristearin), (C) PL:CH (4:1), and (D) PL:SL (2:1).

Figure 3. Response 3D surface plot for the influence of PL:SL weight ratio (X₁), PL:CH molar ratio (X₂), and SL type (X₃) on EE% (Y₃) of VNP emulsomes. (A) SL type (Tripalmitin), (B) SL type (Tristearin), (C) PL:CH (4:1), and (D) PL:SL (2:1).

Figure 4. Response 3D surface plot for the influence of PL:SL weight ratio (X₁), PL:CH molar ratio (X₂), and SL type (X₃) on RE_24h (Y₄) of VNP emulsomes. (A) SL type (Tripalmitin), (B) SL type (Tristearin), (C) PL:CH (4:1), and (D) PL:SL (2:1).

Figure 5. TEM micrographs of (A) optimized VNP emulsomes E12, (B) SA surface-tailored emulsomes E19, and (C) MPEG-DSPE surface-tailored emulsomes E24. Magnification = 22500X.

Figure 6. Release profile of (A) SA and (B) MPEG-DSPE surface-tailored emulsomes in PBS (pH 6.8) at 35 ± 0.5 °C compared to the optimized emulsomes (E12). Results are presented as mean (n = 3) ± SD.

Figure 7. Mean VNP concentration in (A) plasma and (B) brain following the intranasal administration of VNP optimized emulsomes (E12), SA surface-tailored emulsomes (E19) and MPEG-DSPE surface-tailored emulsomes (E24) compared to the orally administered market tablets in rats. Results are presented as mean (n = 6) ± SD.

Table 3. Measured plasma and brain pharmacokinetic parameters of VNP following the intranasal administration of E12, E19, and E24 in comparison with the orally administered market tablets.

	Plasma				Brain
	T max (h)	C max (ng/mL)	AUC(0-12) (ng/mL/h)	AUC(0-∞) (ng/mL/h)	T max (h)	C max (ng/g)	AUC(0-12) (ng/mL/h)	AUC(0-∞) (ng/mL/h)
E12	0.50	547.32 ± 84.53	1293.11 ± 80.43	1492.51 ± 89.60	1.00	1721.41 ± 242.72	4041.70 ± 578.24	4260.97 ± 621.69
E19	0.50	409.05 ± 75.65	1118.87 ± 75.28	1225.85 ± 91.00	1.00	3924.67 ± 627.65	8003.63 ± 1204.84	8195.01 ± 1215.45
E24	0.50	388.46 ± 78.37	1069.27 ± 124.12	1164.86 ± 123.64	1.00	6144.50 ± 968.86	23751.48 ± 1445.82	24914.79 ± 1523.30
Oral VNP	1.00	145.03 ± 27.79	355.91 ± 25.19	361.17 ± 24.63	1.00	73.24 ± 7.79	333.69 ± 31.89	342.07 ± 34.48

Abbreviations: VNP: vinpocetine; C_max: maximum plasma concentration; T_max: time needed to reach the maximum plasma concentration; AUC_0-12: area under the plasma concentration time curve from 0 to 12 h; AUC_0-∞: area under the plasma concentration time curve from 0 to ∞. Results are presented as mean ± SD (n = 6) for C_max, AUC_0-12, and AUC_0-∞ and median (n = 6) for T_max.