Preparation and characterization of isoniazid and lamivudine co-loaded polymeric microspheres

Figures & data

Table I. Composition of various microsphere batches.

Batch No.	Isoniazid (mg)	Lamivudine (mg)	Ethyl cellulose (mg)	Eudragit RS (mg)
A1	300	–	300	–
A2	300	–	600	–
A3	–	300	300	–
A4	–	300	600	–
B1	300	–	–	300
B2	300	–	–	600
B3	–	300	–	300
B4	–	300	–	600
C1	200	200	400	400
C2	200	200	266.66	533.33
C3	200	200	200	600

Figure 1. FTIR spectra of: (a) Isoniazid, (b) lamivudine and (c) physical drug mixture (INH + LAM).

Figure 2. FTIR spectra of: (a) Ethyl cellulose, (b) Eudragit RS, (c) physical mixture of both drugs and polymers (INH + LAM + EC + EU) and (d) microspheres.

Figure 3. DSC thermogram of: (a) Lamivudine, (b) isoniazid, (c) Eudragit RS, (d) ethyl cellulose and (e) combined microspheres.

Figure 4. (a) Digital microscopic images of microspheres of optimized batch. (b) Digital microscopic images of co-loaded microspheres.

Figure 5. SEM images of: (a) EC microspheres, (b) EU microspheres, (c) combined microspheres at 200 × magnified surface of combined microspheres at (d) 500 × (e) 1000 × and (f) 5000×.

Table II. Particle size and yield of different batches of LAM and INH microspheres (n = 3).

Batch code	Particle size (μm ± SD*)	Yield (% ± SD*)
A1	210 ± 1.02	60.23 ± 1.02
A2	279 ± 1.54	86.50 ± 1.11
A3	216 ± 1.85	65.40 ± 0.86
A4	287 ± 1.23	82.74 ± 0.98
B1	220 ± 1.56	56.89 ± 0.77
B2	298 ± 1.85	83.75 ± 1.32
B3	225 ± 1.47	58.20 ± 0.65
B4	301 ± 0.98	82.43 ± 0.78
C1	510 ± 1.73	85.27 ± 0.89
C2	526 ± 0.069	90.65 ± 1.76
C3	532 ± 1.62	92.50 ± 2.01

*SD, standard deviation.

Figure 6. Bar graph representation of entrapment efficiency and loose surface crystal. Values are expressed in percentage. Vertical bars represent average value ± standard deviation.

Figure 7. The cumulative percent of drug release from microspheres in phosphate buffer pH 7.4: (a) EC microspheres, (b) EU microspheres, and (c) combined microspheres.

Table III. Kinetic analysis of in vitro release data.

Model batches	Zero-order		First-order		Higuchi		Korsmeyer–Peppas
	R^2	K0 (%/h)	R^2	K1(h^−1)	R^2	Kh(%/h^1/2)	R^2	n
A1	0.735	5.649	0.842	0.0032	0.996	17.998	0.997	0.268
A2	0.769	5.103	0.827	0.0034	0.996	15.880	0.992	0.261
A3	0.735	5.252	0.838	0.0731	0.995	16.453	0.997	0.249
A4	0.785	4.877	0.769	0.0039	0.998	19.192	0.987	0.272
B1	7.254	5.401	0.939	0.0243	0.996	15.583	0.995	0.237
B2	0.728	5.148	0.952	0.0254	0.996	14.864	0.990	0.245
B3	0.756	4.886	0.914	0.0263	0.994	15.583	0.997	0.239
B4	0.773	4.571	0.969	0.0263	0.996	13.827	0.979	0.251
C1(LAM)	0.917	4.516	0.924	0.0257	0.999	18.453	0.994	0.281
C2(LAM)	0.917	4.785	0.905	0.0302	0.998	19.480	0.999	0.334
C3(LAM)	0.917	4.575	0.886	0.0315	0.993	18.650	0.995	0.352
C1(INH)	0.930	4.561	0.9273	0.0266	0.999	18.434	0.996	0.287
C2(INH)	0.922	4.671	0.919	0.0298	0.998	18.783	0.997	0.324
C3(INH)	0.911	4.813	0.9061	0.0330	0.995	18.601	0.996	0.316

Figure 8. The percent cell viability of Caco-2 cells and DAPI-stained cells. S1, sample after 6 h; S2, sample after 12 h; S3, sample after 24 h.