Strategies to enhance oral delivery of amphotericin B: a comparison of uncoated and enteric-coated nanostructured lipid carriers

Figures & data

Figure 1. TEM micrographs of freshly prepared AmB-NLCs (A) uncoated-NLCs; (B) 5%Eu-NLCs, and (C) 7.5%Eu-NLCs.

Figure 2. Photographs of uncoated NLCs and Eu-NLCs after lyophilization; (A) uncoated-NLCs; (B) 5%Eu-NLCs, and (C) 7.5%Eu-NLCs.

Table 1. Physicochemical characteristics of AmB-NLCs.

Formulations	Before lyophilization			After lyophilization
	Mean size ± SD (nm)	PI ± SD	ZP (mV) ± SD	Mean size ± SD (nm)	PI ± SD	ZP (mV) ± SD	Entrapment ± SD (%)
Uncoated-NLCs	129.8 ± 4.6	0.31 ± 0.01	−30.7 ± 2.2	174.6 ± 11.5*	0.32 ± 0.01	−33.8 ± 0.6	77.5 ± 3.0
5%Eu-NLCs	477.9 ± 44.0	0.33 ± 0.03	−51.2 ± 5.0	643.5 ± 41.9*	0.25 ± 0.04	−53.0 ± 2.3	76.9 ± 1.3
7.5%Eu-NLCs	440.2 ± 28.9	0.35 ± 0.04	−49.8 ± 2.1	483.9 ± 12.1	0.32 ± 0.02	−50.6 ± 0.3	74.5 ± 1.3

Data were presented as mean ± SD; n = 3.

*Indicate statistically significant differences between before and after lyophilization, p  <  0.05 (one-way ANOVA followed by Tukey's test).

Table 2. Solubility of AmB-NLCs in different dissolution medium.

Dissolution medium	Solubility (µg mL^−1) ± SD
	Free drug	Uncoated NLCs	5%Eu-NLCs	7.5%Eu-NLCs
Water	0.70 ± 0.02*	2.65 ± 0.08**	8.09 ± 0.50***	6.71 ± 0.03****
FaSSIF	0.43 ± 0.04*	2.04 ± 0.17**	2.83 ± 0.10***	2.66 ± 0.23***

Data were presented as mean ± SD; n = 3.

Different stars indicated statistically significant differences between formulations in each dissolution medium, p < 0.05 (one-way ANOVA followed by Tukey’s test).

Figure 3. %Cumulative drug released from (

) free AmB, (

) uncoated NLCs, (

) 5%Eu-NLCs and (

) 7.5%Eu-NLCs in different dissolution medium; (A) FaSSGF and (B) FaSSIF (Data were presented as mean ± SD, n  =  3).

Table 3. The percentage of AmB in apical side, basolateral side, and cell monolayer after 6-h incubation.

Formulations	AmB (%) ± SD
	Apical side	Caco-2 cells	Basolateral side
Free AmB	70.49 ± 2.93^a	8.74 ± 0.44^a	ND
Uncoated NLCs	87.33 ± 2.93	4.85 ± 0.09^b	1.30 ± 0.48
5%Eu-NLCs	84.70 ± 3.43	1.14 ± 0.15^c	0.33 ± 0.02
7.5%Eu-NLCs	89.35 ± 1.96	1.27 ± 0.22^c	0.47 ± 0.07

Data were presented as mean ± SD; n = 3. a, b, and c = different letters present statistical difference p < 0.05 (one-way ANOVA followed by Tukey's test). ND: not detected.

Figure 4. Apparent permeability coefficient of uncoated NLCs and Eu-NLCs across Caco-2 cell monolayers. Data were presented as mean ± SD; n = 3. *, ** are different letters present statistical difference, p <  0.05 (one-way ANOVA followed by Tukey's test).

Table 4. Mean size of AmB-NLCs after 3 and 6 months at 4 °C and RT in the absence of the day light.

Temperature	Storage time	Mean particle size (nm) ± SD
		Uncoated NLCs	5%Eu-NLCs	7.5%Eu-NLCs
RT	Initial	174.6 ± 11.5	643.5 ± 41.9	483.9 ± 12.1
	3 months	173.7 ± 19.4	699.8 ± 19.9	509.2 ± 16.8
	6 months	190.9 ± 4.1	701.7 ± 10.4	482.8 ± 9.9
4 °C	3 months	181.1 ± 13.1	677.5 ± 17.8	499.6 ± 13.8
	6 months	187.2 ± 15.4	692.5 ± 19.3	494.8 ± 7.6

Data were presented as mean ± SD; n = 3. RT: room temperature.

Table 5. Zeta potential of AmB-NLCs after 3 and 6 months at 4 °C and RT in the absence of the day light.

Temperature	Storage time	Zeta potential (mV) ± SD
		Uncoated NLCs	5%Eu-NLCs	7.5%Eu-NLCs
RT	Initial	−33.8 ± 0.6	−53.0 ± 2.3	−50.6 ± 0.3
	3 months	−33.6 ± 1.8	−52.8 ± 1.7	−51.0 ± 1.1
	6 months	−32.8 ± 1.3	−51.8 ± 1.5	−51.8 ± 0.6
4 °C	3 months	−34.0 ± 3.0	−51.7 ± 1.5	−48.8 ± 3.3
	6 months	−32.8 ± 1.0	−52.6 ± 1.2	−52.2 ± 1.2

Data were presented as mean ± SD; n = 3. RT: room temperature.

Figure 5. Percentage of drug remaining of uncoated NLCs and Eu-NLCs storage at 4 °C and RT after 3 and 6 months. (Data were presented as mean ± SD, n  =  3).