Enhanced oral bioavailability of cyclosporine A by liposomes containing a bile salt

Figures & data

Table 1 Formulation details of SPC/SDC and SPC/Chol liposomes for in vitro release and in vivo bioavailability studies (n = 3)

Liposome type	SPC/SDC (Chol) ratio	Theoretical SPC concentration (%, w/v)	Theoretical CyA loading (mg/mL)	Particle size (nm)	Polydispersity	Zeta potential (mV)	Entrapment efficiency (%)
SPC/SDC	3/1	5	2	85.6 ± 1.0	0.064 ± 0.013	−35.25 ± 4.42	94.05 ± 2.76
SPC/Chol	5/1	5	2	98.1 ± 2.3	0.117 ± 0.032	−32.09 ± 3.82	95.22 ± 3.02

Abbreviations: Chol, cholesterol; CyA, cyclosporine A; SPC, soybean phosphatidylcholine; SDC, sodium deoxycholate.

Figure 1 The effects of homogenization factors on particle size and PI of CyA-loaded SPC/SDC liposomes. Typical size distribution of CyA-loaded SPC/SDC liposomes before (A) or after (B) homogenization is shown. Particle size and PI with different factors including homogenization pressure (^▴▴P < 0.01 comparing PI at 100 and 150 bar; ^▴▴▴P < 0.001 comparing PI at 100 and 150 bar) (C) and homogenization cycles (D) are shown. Data are presented as mean ± SD (n = 3).

Abbreviations: Chol, cholesterol; CyA, cyclosporine A; PI, polydispersity index; SPC, soybean phosphatidylcholine; SDC, sodium deoxycholate.

Figure 2 Effect of formulation variables on the particle size and PI of CyA-loaded SPC/SDC liposomes. Ratio of SPC/SDC (A) (***P < 0.001 comparing particle size in each of the two groups; ***P < 0.001 comparing PI at the ratio of 3/1 and 4/1); concentration of SPC (B) (**P < 0.01 comparing particle size in each of the two groups; ^▴P < 0.05 comparing PI in each of the two groups.); CyA loading (C) (**P < 0.01 comparing particle size in each of the two groups; ^▴▴▴P < 0.001 comparing PI in each of the two groups). Data are presented as mean ± SD (n = 3).

Abbreviations: Chol, cholesterol; CyA, cyclosporine A; PI, polydispersity index; SPC, soybean phosphatidylcholine; SDC, sodium deoxycholate.

Figure 3 Effect of formulation variables on the entrapment efficiency of CyA-loaded SPC/SDC liposomes. SPC/Chol (A) (*P < 0.05 comparing SPC/Chol ratio 3/1 and 4/1); concentration of SPC (B) (*P < 0.05 comparing SPC concentration 1% and 2%; **P < 0.01 comparing SPC concentration 1% and 2%); CyA loading (C) (**P < 0.01 comparing any other group). Data are presented as mean ± SD (n = 3).

Abbreviations: Chol, cholesterol; CyA, cyclosporine A; PI, polydispersity index; SPC, soybean phosphatidylcholine; SDC, sodium deoxycholate.

Table 2 The stability of SPC/SDC liposomes for 7 days stored in 4°C (n = 3)

Time (days)	Entrapment efficiency (%)	Particle size (nm)	Polydispersity	Zeta potential (mV)
0	93.27 ± 3.85	87.2 ± 2.1	0.074 ± 0.015	−33.05 ± 2.79
1	94.72 ± 2.41	85.3 ± 1.9	0.071 ± 0.009	−35.22 ± 3.42
4	92.53 ± 3.21	88.9 ± 2.0	0.080 ± 0.019	−33.56 ± 3.75
7	90.38 ± 4.33	90.2 ± 3.4	0.085 ± 0.013	−30.45 ± 3.69

Abbreviations: SPC, soybean phosphatidylcholine; SDC, sodium deoxycholate.

Figure 4 TEM morphology of CyA-loaded SPC/SDC liposomes.

Abbreviations: CyA, cyclosporine A; SPC, soybean phosphatidylcholine; SDC, sodium deoxycholate.

Figure 5 In vitro release of CyA from SPC/SDC, SPC/Chol liposomes, and Sandimmune Neoral. Data are presented as mean ± SD (n = 3).

Abbreviations: Chol, cholesterol; CyA, cyclosporine A; SPC, soybean phosphatidylcholine; SDC, sodium deoxycholate.

Table 3 Pharmacokinetic parameters after oral administration of CyA-loaded SPC/SDC, SPC/Chol liposomes and Sandimmune Neoral (n = 6)

Formulation	Tmax (h)	Cmax (μg/mL)	t1/2 (h)	AUC0–t (μg · h/mL)	AUC0−∞ (μg · h/mL)	MRT (h)	Relative bioavailability*
SPC/SDC liposomes	4.67 ± 1.49	2.65 ± 0.70	20.54 ± 7.63	42.16 ± 6.30	73.90 ± 6.63	10.73 ± 0.90	120.3%
SPC/Chol liposomes	2.67 ± 0.69	2.28 ± 0.31	19.84 ± 6.50	34.56 ± 4.08	60.49 ± 10.79	10.42 ± 0.37	98.6%
Sandimmun Neoral^®	2.67 ± 0.69	2.57 ± 0.20	19.09 ± 10.15	35.02 ± 4.68	65.41 ± 29.55	10.23 ± 0.64

Note:

* Relative bioavailability (%) of the liposomes calculated on AUC_0−t with Sandimmune Neoral as the reference.

Abbreviations: Chol, cholesterol; CyA, cyclosporine A; soybean phosphatidylcholine; SDC, sodium deoxycholate; MRT, maximum retention time.

Figure 6 Plot of blood CyA concentration versus time after a single oral dose of 15 mg/kg equivalent SPC/SDC, SPC/Chol liposomes and Sandimmune Neoral in rats. Data are presented in mean ± SD (n = 6).

Abbreviations: Chol, cholesterol; CyA, cyclosporine A; SPC, soybean phosphatidylcholine; SDC, sodium deoxycholate.