Preparation and characterization of a coacervate extended-release microparticulate delivery system for Lactobacillus rhamnosus

Figures & data

Table 1 Formulation formulae and values of evaluation parameters of all formulation batches

Formulation code/parameter	F1	F2	F3	F4	F5	F6
Grade of Methocel Premium used	E5–LV	E5–LV	E15–LV	E15–LV	E10M–CR	E10M–CR
Lactobacillus rhamnosus to polymer ratio	1:1	1:2	1:1	1:2	1:1	1:2
Percent yield (w/w)^a	58.18 ± 1.98	49.21 ± 1.89	54.91 ± 1.86	45.46 ± 1.63	49.32 ± 1.83	41.24 ± 1.76
Entrapment efficiency (% cfu/g)^a	64.16 ± 1.53	57.25 ± 1.81	58.42 ± 1.96	52.62 ± 1.79	51.84 ± 1.86	45.18 ± 1.73
Mean particle size (μm)^a	33.10 ± 1.32	35.90 ± 1.53	36.45 ± 1.58	44.23 ± 1.96	46.32 ± 2.02	49.62 ± 1.87
Zeta potential (mV)^a
Uncoated microparticles	−19.2 ± 0.3	−19.1 ± 0.5	−19.3 ± 0.7	−19.4 ± 0.4	−18.9 ± 0.9	−19.3 ± 0.8
Coated microparticles	−11.6 ± 0.3	−11.6 ± 0.8	−11.4 ± 0.9	−11.3 ± 0.6	−11.8 ± 0.6	−11.2 ± 0.7
Percent swelling^a	1.38 ± 0.049	1.24 ± 0.046	1.13 ± 0.039	1.03 ± 0.043	0.88 ± 0.038	0.82 ± 0.031
Percent adhesive strength^a	73.36 ± 1.32	68.86 ± 1.53	62.64 ± 1.71	55.51 ± 1.46	48.71 ± 1.34	42.61 ± 1.42
Percent mucoadhesion^a	75.92 ± 1.57	69.31 ± 1.65	61.35 ± 1.43	54.79 ± 1.54	49.52 ± 1.24	44.43 ± 1.33
Zero-order kinetic constants
Regression coefficient (r^2)	0.9834	0.9947	0.9892	0.9916	0.9932	0.9875
Proportionality constant (K0)	6.3842	5.1419	3.7874	4.3137	3.3727	2.6908
First-order kinetic constants
Regression coefficient (r^2)	0.5863	0.7402	0.6524	0.8446	0.8178	0.7365
Release rate constant (K)	0.0413	0.0460	0.0411	0.0485	0.0449	0.0382
Hixson-Crowell model kinetic constants
Regression coefficient (r^2)	0.8993	0.9912	0.9928	0.9903	0.9971	0.9914
Surface-volume relation constant (Ks)	0.3289	0.1129	0.1008	0.0849	0.0627	0.0488
Weibull model kinetic constants
Scale parameter (α)	69.324	47.422	48.651	34.893	29.445	26.361
Shape parameter (β)	1.8397	1.2381	1.5977	1.0823	1.1826	1.5970
Location parameter (Td)	10.015	22.575	11.375	26.637	17.467	7.7580
Regression coefficient (r^2)	0.9428	0.9399	0.9402	0.9310	0.9449	0.9670

Note:

a Data presented as mean value ± standard error, n = 3.

Figure 1 Scanning electron microscopy photographs of microparticles from formulation batches (A) F1, (B) F3, and (C) F5.

Figure 2 Histogram of mean particle size distribution of all formulation batches.

Figure 3 Zeta potential report of uncoated microparticles from formulation batch F1.

Figure 4 Comparative in vitro release profile of viable Lactobacillus rhamnosus cells from coated microparticles of all formulation batches in simulated intestinal fluid TS, following zero-order kinetics.

Table 2 Values of the dissimilarity factor (f₁), the similarity factor (f₂) and the two indices of Rescigno (ξ₁ and ξ₂)

Model-independent factors	Formulation pair
	F1 vs F2	F1 vs F3	F1 vs F5	F2 vs F4	F2 vs F6	F3 vs F4	F5 vs F6	F4 vs F6
ξ1	0.102	0.137	0.328	0.133	0.299	0.098	0.070	0.173
ξ2	0.290	0.248	0.407	0.245	0.334	0.259	0.240	0.335
f1	33.00	30.78	58.00	24.64	43.00	27.00	17.00	29.84
f2	36.00	36.78	24.00	50.14	36.00	48.00	68.00	48.99