Development and characterization of PLGA nanoparticles as delivery systems of a prodrug of zidovudine obtained by its conjugation with ursodeoxycholic acid

Figures & data

Figure 1. Chemical formula of AZT, UDCA and their prodrug UDCA–AZT obtained by ester-conjugation.

Table 1. Formulation parameters, size and physical–chemical characteristics of NPs obtained by nanoprecipitation technique.

Batch	Samples	UDCA–AZT (mg)	Pluronic-F68 (mg)	Water phase (mL)	Particle size nm ± SD	PDI	ζ potential (mV)	Actual loading (%)	Pluronic residual (%, w/w)
NP1	UN1P	–	50	20	527 ± 143	0.525	−24.7	–	0.9 ± 0.3
Purified by ultrafiltration	LO1P	2.5	50	20	1214 ± 560	0.792	−22.2	0.79 ± 0.05	0.8 ± 0.2
NP2	UN1	–	50	60	712 ± 210	0.606	−26.4		33.0 ± 1.2
Unpurified	LO1	2.5	50	60	576 ± 120	0.389	−27.3	0.78 ± 0.04	34.5 ± 2.2
NP3	UN1	–	–	60	704 ± 312	0.553	−28.1	–	–
Unpurified	LO1	2.5	–	60	791 ± 69	0.638	−22.2	0.051	–
NP2
Unpurified	LO2	6.0	50	60	597 ± 172	0.573	−13.6	1.53 ± 0.07	33.0 ± 1.1
NP2
Purified by gel filtration	LO2P	6.0	50	60	753 ± 150	(0.627)	−28.4	0.84 ± 0.04	0.5 ± 0.2

In each sample, 100 mg of PLGA dissolved in 4 mL of organic phase (acetone) was employed. Loading and particle size data are reported as the mean ± SD of three independent experiments.

Table 2. Formulation parameters, size and physical–chemical characteristics of NPs obtained by emulsion/solvent evaporation technique.

Batch	Samples	UDCA–AZT (mg)	Pluronic-F68 (mg)	Water phase (mL)	Organic phase (mL)	Particle sizenm ± SD	PDI	ζ poten-tial (mV)	Actual loading	Pluronic residual (%,w/w)
EM1	UN1P	–	100	10	1	412 ± 89	0.243	−16.9	–	0.8 ± 0.2
Purified	LO1P	2.5	100	10	1	1201 ± 470	0.760	−18.7	0.83 ± 0.06	0.9 ± 0.3
EM2	UN1	–	50	30	2	850 ± 149	0.592	−13.2	–	28.5 ± 1.3
Unpurified	LO1	2.5	50	30	2	447 ± 30	0.479	−19.3	0.80 ± 0.05	27.3 ± 1.6

In each sample 125 mg of PLGA dissolved in diclorometane was employed. Loading and particle size data are reported as the mean ± SD of three independent experiments.

Figure 2. Particle mass distributions of the samples. (A) NP1-UN1P and NP1-LO1P; (B) NP2-UN2 and NP2-LO2 and (C) EM1-UN1P and EM1-LO1P. The conversion from the fractograms was achieved by setting a particle density of 1.3 g/mL for all samples. The fractionations were obtained under programed field conditions by using a 0.01% w/v solution of Triton X-100 as mobile phase, flowing at 2 mL/min.

Figure 3. SEM micrographs of the samples NP1 -LO1P (A), NP2-LO2P (B), obtained by nanoprecipitation and EM 1-UN1 (C), obtained by emulsion–solvent evaporation method.

Figure 4. In vitro release of UDCA–AZT from PLGA NP, obtained by nanoprecipitation (A) or emulsion/solvent evaporation (B) methods. The release profiles are compared with those of the raw UDCA–AZT powder dissolution during time in the absence or in the presence of 0.5% Pluronic F-68. Results are the means of three independent experiments.

Figure 5. Degradation profiles of the free prodrug UDCA−AZT in rat liver homogenates in the absence or in the presence of unloaded nanoparticulate systems obtained by nanoprecipitation. All the values are reported as the percentage of the overall amount of incubated prodrug. Data are reported as the mean ± SD of four independent experiments.

Figure 6. Degradation in rat liver homogenates of free or encapsulated UDCA–AZT in PLGA NP. All UDCA–AZT and AZT values are reported as the percentage of the overall amount of incubated prodrug. Data are reported as the mean ± SD of four independent experiments.