Controlled delivery of the popular nonsteroidal anti-inflammatory drug, paracetamol, from chitosan-g-polyacrylamide microspheres prepared by the emulsion crosslinking technique

Figures & data

Table I. Preparation conditions and characterization of the paracetamol-loaded microspheres.

Formulation Code	CS-g-PAAm Concentration (w/v)	GA (mL)	Paracetamol/polymer (w/w) ratio	EE (%)	Microsphere Size (μm)	ESD (%) (at pH 1.2)
P1	1	2	1/1	47.46	96.0 ± 16.2	261.90
P2	1	3	1/1	34.02	94.0 ± 11.1	192.71
P3	1	5	1/1	31.89	78.0 ± 16.6	183.11
P4	1	2	1/3	57.18	126.0 ± 13.5	215.73
P5	1	3	1/3	53.37	113.0 ± 15.5	161.61
P6	1	5	1/3	41.05	96.0 ± 19.1	114.86
P7	1	2	1/5	70.20	170.0 ± 25.7	154.68
P8	1	3	1/5	63.66	149.0 ± 28.4	131.11
P9	1	5	1/5	54.55	122.0 ± 16.0	65.85
P10	1.5	3	1/5	70.28	242.0 ± 18.9	95.72
P11	2.0	3	1/5	72.61	252.0 ± 8.7	92.82

Figure 1. DSC thermograms of paracetamol (a), paracetamol-loaded CS-g-PAAm microspheres (b), and empty CS-g-PAAm microspheres (c).

Figure 2. FTIR results of CS-g-PAAm (a), paracetamol (b), CS-g-PAAm empty microspheres (c), and paracetamol-loaded CS-g-PAAm microspheres (d).

Scheme 1. Chemical structure of paracetamol.

Figure 3. SEM micrographs of (a) dried paracetamol-loaded microsphere at 1500x, (b) surface of the dried paracetamol-loaded microsphere at 30,000x, (c) dried empty microsphere at 960x, and (d) surface of the empty microsphere at 30,000x.

Table II. Parameters of release kinetics of different formulations.

Formulation Code	D×10^12 (cm^2/s)	k (min^−n)	n	r	Diffusion Mechanism
P1	13.15	0.0758	0.9160	0.9992	Case II transport
P2	9.33	0.0631	0.9053	0.9991	Case II transport
P3	7.88	0.0724	0.8984	0.9989	Case II transport
P4	23.20	0.0766	0.9158	0.9925	Case II transport
P5	16.40	0.0723	0.9147	0.9925	Case II transport
P6	11.77	0.0728	0.9011	0.9991	Case II transport
P7	38.94	0.0737	0.9157	0.9992	Case II transport
P8	28.73	0.0734	0.9122	0.9919	Case II transport
P9	15.92	0.0651	0.9028	0.9991	Case II transport
P10	58.92	0.0648	0.8925	0.9977	Case II transport
P11	59.39	0.0558	0.8044	0.9853	Non-Fickian transport

Figure 4. Effect of amount of GA on paracetamol release. CS-g-PAAm concentration: 1%, paracetamol/polymer ratio: 1/1, exposure time to GA: 2 h.

Figure 5. Effect of amount of GA on paracetamol release. CS-g-PAAm concentration: 1%, paracetamol/polymer ratio: 1/3, exposure time to GA: 2 h.

Figure 6. Effect of amount of GA on paracetamol release. CS-g-PAAm concentration: 1%, paracetamol/polymer ratio: 1/5, exposure time to GA: 2 h.

Figure 7. Effect of paracetamol/polymer ratio on paracetamol release. CS-g-PAAm concentration: 1%, amount of GA: 2 mL, exposure time to GA: 2 h.

Figure 8. Effect of paracetamol/polymer ratio on paracetamol release. CS-g-PAAm concentration: 1%, amount of GA: 3 mL, exposure time to GA: 2 h.

Figure 9. Effect of paracetamol/polymer ratio on paracetamol release. CS-g-PAAm concentration: 1%, amount of GA: 5 mL, exposure time to GA: 2 h.

Figure 10. Effect of CS-g-PAAm concentration on paracetamol release. Paracetamol/polymer ratio: 1/5, amount of GA: 3 mL, exposure time to GA: 2 h.

Table III. Equilibrium swelling degree (% ESD) for the empty microspheres.

Formulation Code	GA (mL)	pH 1.2	pH 7.4
A	2	73.96 ± 2.50	14.74 ± 1.47
B	3	52.27 ± 0.27	10.62 ± 1.49
C	5	36.81 ± 0.90	8.60 ± 2.92