Table 3. Effect of drug: polymer ratio, stirring rate, Emulsifier and dispersing medium on the drug content, production yield and particle size of anhydrous theophylline microspheres.
| Parameter | Characteristics | ||||||
| Formulation code | Process variable | Production yield (%±SD) | Theoretical drug content (%) | Mean drug entrapped (%) | Mean particle Size (µm ± SD) | Drug loading efficiency (%±SD) | |
| Polymer: Drug ratio |
F1 F2 F3 F4 *F5 |
2:1 3:1 4:1 5:1 6:1 |
90.50±2.24 91.83±3.24 99.63±3.08 99.90±3.13 92.83±4.12 |
33.33 25 20 16.67 14.29 |
25.3±0.65 17.48±3.93 14.01±2.53 10.53±4.13 8.67±1.32 |
352.76±1.68 286.08±1.67 248.09±1.59 225.57±1.36 205.93±1.53 |
75.92±12.3 69.91±1.90 70.05±12.6 63.18±15.7 60.67±9.50 |
| Stirring rate (rpm) |
F5-1 *F1-2 F5-3 |
200 400 600 |
-
92.83±4.12 6.19 ±91.65 |
-
14.29 14.29 |
-
8.67±1.32 0.27±13.40 |
-
375.93±1.53 300.88±1.86 |
-
60.67±9.5 95.74±1.59 |
| Emulsifier concentration (%) |
F5-4 *F5-5 F5-6 |
1 3 5 |
1.24 ±81.01 92.83±4.12 6.59 ±92.83 |
14.29 14.29 14.29 |
0.32± 7.61 8.67±1.32 8.04±0.87 |
1.69±398.88 375.93±1.53 234.75 ±1.68 |
54.36±1.88 60.67±9.50 57.43±0.05 |
| Volume of dispersing medium (ml) |
F5-7 *F5-8 F1-9 |
100 200 300 |
1.24±94.43 92.83±4.12 77.47±3.22 |
14.29 14.29 14.29 |
8.57±1.19 8.67±1.32 10.05±0.48 |
1.71±303.76 375.93±1.53 219.36±1.76 |
59.97±0.57 60.67±9.50 70.36±2.80 |