In Vitro Performance of Carbamazepine Loaded to Various Molecular Weights of Poly (D, L-Lactide-Co-Glycolide)

Figures & data

TABLE 1 The effect of formulations on Cadrbamzepine microspheres characteristics

Formulations CBZ : polymer ratio	Yield (%)	Encapsulation (%)	Mean diameter (μm)
RG858
1:2	89.9 ± 9.5	82.1 ± 7.2	315 ± 31
1:3	88.2 ± 7.3	80.5 ± 9.1	356 ± 25
1:4	75.1 ± 10.2	77.7 ± 6.3	426 ± 30
R208
1:3	75.2 ± 8.1	68.2 ± 7.3	324 ± 45
RG506
1:3	87.4 ± 8.9	77.4 ± 6.7	298 ± 29
RG858: R208
1:1	82.0 ± 10.1	81.5 ± 8.4	453 ± 40
1:2	83.1 ± 6.7	78.2 ± 7.9	307 ± 35
2:1	82.8 ± 5.9	79.4 ± 6.8	434 ± 20
RG506:R208
1:1	85.7 ± 5.4	70.1 ± 6.3	415 ± 39
1:2	88.7 ± 7.5	73.7 ± 8.1	386 ± 24
2:1	83.1 ± 8.8	78.5 ± 7.2	325 ± 36

*Drug: polymer mixture ratio = 1:3.

FIG. 1 INfrared spectra of CBZ, PLGA, and CBZ loaded to PLGA, where: A = Pure CBZ, B = RG506, C = RG 858, D = CBZ:RG 506 (1:3) microspheres and E = CBZ:RG 506 (1:3) microspheres.

FIG. 2 Differential scanning calorimetry of CBZ, PLGA microspheres where: A = Pure CBZ, B = RG506, C = R208, D = RG858, E = CBZ:(RG858 + 208) 1:3, and F = CBZ:(RG858 + 506) 1:3.

FIG. 3 The electron scanning micrographs of CBZ-PLGA microspheres, in the presence “A” or absence “B” of pluronic (0.5%) in the formulation process, respectively.

FIG. 4 The in vitro release of CBZ loaded to microspheres prepared with polymers with different Lacide and glycolide content.

FIG. 5 The effect of 0.5% Pluronic F-68 (P) on the in vitro release of CBZ from CBZ-PLGA (RG 858) prepared in different ratios.

FIG. 6 The in vitro release profile of CBZ from mixtures of RG858 + R208 PLGA-PLA-based microspheres in the presence of 0.5% Pluronic F-68.

FIG. 7 The in vitro release profile of CBZ from mixtures of RG506 + R208 PLGA-PLA = based microspheres in the presence of 0.5% Pluronic F-68.

TABLE 2 Mean release kinetic parameters of carbamazepine from different microsphere formulations

Formula Kinetic	1:3 (RG858)	1:3 (RG506)	1:3 (R208)	1:3 (RG858+, R208, 1:1)	1:3 (RG858+ R208, 1:2)	1:3 (RG858+ R208, 2:1)	1:3 (RG506+ R208, 1:1)	1:3 (RG506+ R208, 1:2)	1:3 (RG506+ R208, 2:1)
First order
r	0.842	0.927	0.968	0.769	0.753	0.903	0.895	0.909	0.854
k	0.036	0.066	0.012	0.050	0.022	0.041	0.087	0.067	0.048
Zero order
r	0.709	0.813	0.846	0.634	0.674	0.809	0.774	0.796	0.592
k	1.817	2.216	1.072	2.057	1.394	2.198	3.149	2.859	2.419
Higuchi model
r	0.991	0.998	0.982	0.927	0.962	0.958	0.944	0.969	0.968
k	7.864	8.949	7.864	9.489	6.249	10.806	16.483	14.659	11.161
Peppas model
r	0.990	0.990	0.980	0.958	0.994	0.916	0.965	0.970	0.944
n	0.439	0.419	0.339	0.469	0.398	0.505	0.388	0.476	0.476
T50% (h)	3.90	0.25	>24	18.3	22.2	7.2	3.25	5.0	1.5

k = Release rate constants n = Release exponent (Peppas model), and T_50%: Dissolution half-life. r = correlation coefficient's.