Optimization, ex vivo permeation, and stability study of lipid nanocarrier loaded gelatin capsules for treatment of intermittent claudication

Figures & data

Table 1 Compositions, % transmittance, globule size, emulsification times, and solubility of the investigated SNEF

Formulation code	% Oil mix (BL/CP)	% SG	% Transcutol^®	% Transmittance	Globule size (nm)	Emulsification time (seconds)	Solubility (mg/mL)
A1	70	30	0	6.6	65.63	150	7.96
A2	60	40	0	76.4	50.4	165	7.60
A3	50	50	0	95.1	17.69	270	6.79
A4	40	60	0	96.8	15.27	420	6.38
A5	30	70	0	98.5	14.56	121	5.94
A6	20	80	0	99.7	12.2	670	6.38
B1	60	30	10	61.4	56	420	9.65
B2	50	37.5	12.5	90.6	35.7	190	8.58
B3	40	45	15	94.2	25.46	182	7.81
B4	30	52.5	17.5	97.3	17.54	90	7.62
B5	20	60	20	99.2	15.4	640	7.12
C1	60	26.67	13.33	59.7	58	330	9.86
C2	50	33.33	16.67	80.5	53.95	225	9.54
C3	40	40	20	92	40.28	128	9.11
C4	30	46.67	23.33	96.4	20.12	660	8.86
C5	20	53.33	26.67	99.7	16.2	520	6.88
D1	60	20	20	5	92.4	310	12.37
D2	50	25	25	3	97.38	230	10.65
D3	40	30	30	82.5	52.7	182	10.99
D4	30	35	35	92.7	22.52	128	8.13
D5	20	40	40	99.3	20.2	180	7.69

Abbreviations: BL, butyl lactate; CP, Capryol^® 90; SG, Solubilisant Gamma^® 2429; SNEF, self-nanoemulsifying formulation.

Figure 1 Ternary phase diagram of butyl lactate/Capryol^®/Solubilisant Gamma^® and Transcutol^®.

Abbreviations: BL, butyl lactate; CP, Capryol^® 90.

Figure 2 Solubility of CZL in various oils, surfactants and co-surfactants.

Abbreviations: CZL, cilostazol; SG, Solubilisant Gamma^® 2429.

Table 2 Emulsification efficiency of various surfactants

Surfactant	Capryol^® 90	CP/BL (1:1)	LG/BL (1:1)
Chremophor^® RH40	99.5±0.22	99.5±0.08	89.3±0.25
Tween^® 20	94.9±0.54	99.1±0.04	83.02±0.28
Tween^® 60	93.9±0.24	98.1±0.14	87.4±0.40
Labrasol^®	62.1±0.59	71.1±0.37	19.4±6.03
Solubilisant Gamma^® 2429	99.5±0.42	99.7±0.08	85.4±0.18

Note: All data are presented as mean ± standard deviation.

Abbreviations: BL, butyl lactate; CP, Capryol^® 90; LG, Lauroglycol^® 90.

Table 3 Emulsification efficiency of surfactant/co-surfactant combinations

Co-surfactant	% Transmittance
	Chremophor^® RH40		Solubilisant Gamma^® 2429
	Capryol^® 90	LG/BL (1:1)	CP/BL (1:1)
Ethanol	99.6±0.13	96.2±0.99	99.5±0.05
Propylene glycol	99.2±0.1	96.7±0.13	99.3±0.17
Plurol Oleique^®	98.5±0.05	65.1±0.63	99.3±0.07
Transcutol^®	99.6±0.07	96.8±0.47	99.8±0.04

Note: All data are presented as mean ± standard deviation.

Abbreviations: BL, butyl lactate; CP, Capryol^® 90; LG, Lauroglycol^® 90.

Figure 3 Correlation between globule size analysis and % transmittance of diluted PCs.

Abbreviation: PCs, preconcentrates.

Table 4 Regression results and statistical analysis of measured responses

Model	Coefficient	Y1	Y2	Y3	Y4	Y5	Y6
	Intercept	8.63037	32.9352	94.003	253.373	79.8276	91.1356
	b1 (X1)	1.72967	37.8678	−49.0513	−33.7279	29.1534	6.47895
	b2 (X2)	−1.82571	−19.9756	19.544	13.5192	−8.56634	−9.38351
	b3 (X1 X2)	−0.89123	−14.3774	18.023	−162.429		36.2118
	b4 (X1)^2		14.5803	−37.1461	243.469		−21.8997
	b5 (X2)^2		9.4683	−17.5541	−85.5585		−11.4309
Linear	SD	0.658872	12.46	21.88	181.24	12.35	13.68
	R^2	0.861364	0.7882	0.5924	0.1574	0.7133	0.7594
	Adjusted R^2	0.84596	0.7646	0.5471	0.0638	0.6814	0.7224
	PRESS	11.80032	4,043.12	12,954.78	8.10E+05	3,577.7	3,974.64
Two-factor interaction	SD	0.5	11.68	22.13	177.07	12.71	10.6
	R^2	0.9253	0.8241	0.6061	0.2404	0.7133	0.8667
	Adjusted R^2	0.9121	0.7931	0.5366	0.1064	0.6627	0.8334
	PRESS	6.4	4,099.58	17,596.43	7.69E+05	3,782.93	2,620.21
Quadratic	SD	0.52	9.66	15.74	160.26	13.35	8.44
	R^2	0.9275	0.894	0.8243	0.451	0.7209	0.9295
	Adjusted R^2	0.9033	0.8586	0.7657	0.268	0.6278	0.8943
	PRESS	7.85	2,843.79	10,006.91	6.71E+05	4,606.77	1,649.85
Cubic	SD	0.53	8.43	13.34	170.88	12.04	9.36
	R^2	0.945	0.9407	0.9074	0.5423	0.8336	0.948
	Adjusted R^2	0.9001	0.8923	0.8315	0.1677	0.6975	0.8699
	PRESS	14.16	4,687.62	13,653.77	1.06E+06	5,454.28	9,602.51

Abbreviations: PRESS, predicted residual sum of square; SD, standard deviation.

Figure 4 Response surface plots for (A) solubility; (B) globule size; (C) % transmittance; (D) emulsification time; (E) % of unprecipitated drug; (F) % released after 1 minute as a function of % oil and S/Co-s ratio.

Abbreviations: S/Co-s, ratio of surfactant to co-surfactant.

Figure 5 3D response surface plot for the effect of the three formulation components on percentage of CZL precipitated.

Abbreviations: CZL, cilostazol; ppt, precipitate; SG, Solubilisant Gamma^® 2429; 3D, three-dimensional; Trans, transcutol.

Figure 6 In vitro dissolution of CZL from investigated PCs and pure CZL in phosphate buffer pH 6.8 at 37°C.

Abbreviations: CZL, cilostazol; PCs, preconcentrates.

Figure 7 Response surface plot for the overall desirability (D) as a function of oil percentage and S/Co-s ratio.

Abbreviation: S/Co-s, ratio of surfactant to co-surfactant.

Table 5 Predicted and observed responses of optimized CZL preconcentrates

	Y1	Y2	Y4	Y5	Y6
Predicted	10.35	67.67	316	98.07	83.70
Observed	10.12	62.40	324	97.8	85.41
% Error	2.22	3.56	2.53	0.27	2.04

Abbreviation: CZL, cilostazol.

Figure 8 TEM micrographs of (A) diluted NE preconcentrates and (B) reconstituted SNEGs (×50,000).

Abbreviations: PC, preconcentrate; S/Co-s, ratio of surfactant to co-surfactant; SNEGs, self-nanoemulsifying granules; TEM, transmission electron microscopy; NE, Nanoemulsion.

Figure 9 Scanning electron micrographs of (A) Aerosil^® 200 and (B) SNEGs.

Abbreviation: SNEGs, self-nanoemulsifying granules.

Figure 10 In vitro release profile of CZL from SNEGs, conventional tablet, and drug powder.

Abbreviations: CZL, cilostazol; SNEGs, self-nanoemulsifying granules.

Figure 11 Cumulative percentage of CZL permeated from SNEGs and conventional tablet suspension through non-everted rat intestine at 37°C.

Abbreviations: CZL, cilostazol; SNEGs, self-nanoemulsifying granules.

Figure 12 Log percentage drug remaining versus time plot of CZL-loaded SNEGs.

Abbreviations: CZL, cilostazol; SNEGs, self-nanoemulsifying granules.

Figure 13 Arrhenius plot for CZL–SNEGs.

Abbreviations: CZL, cilostazol; SNEGs, self-nanoemulsifying granules.

Figure 14 Comparative plasma concentration–time profile of CZL after oral administration of SNEGs and commercial tablets to rabbits.

Abbreviations: CZL, cilostazol; SNEGs, self-nanoemulsifying granules.