Stability of methylparaben in formulations F1 and F2 stored at 25°C and at 40°C*
| Time (days) | 25°C±3°C | 40°C±0.5°C | ||
| F1 | F2 | F1 | F2 | |
| 0 (100%) | 1.03±0.03 mg/mL | 1.04±0.02 mg/mL | 1.03±0.03 mg/mL | 1.04±0.02 mg/mL |
| 7 | 100.00±0.15 | 98.06±2.80 | 95.14±2.75 | 89.52±2.26 |
| 30 | 99.03±1.91 | 98.06±0.25 | 97.08±0.81 | 83.50±1.50 |
| 90 | 99.03±1.06 | 96.11±0.47 | 95.14±0.80 | 69.90±1.37 |
| 180 | 98.06±1.41 | 92.29±2.00 | 90.29±0.59 | 52.43±1.06 |
| 270 | 97.12±1.10 | 91.98±0.30 | 89.42±2.21 | 41.75±0.53 |
*Mean ± SD of determinations for four samples (n=4).