Table 3. Stability (ST%) of metronidazole (MET), ceftriaxone (CEF), hydroxymetronidazole (MET-OH) with the coefficient of variation (CV%) in plasma and CEF in ultra-filtrate (CEF uf) (n=5).
| MET | CEF | MET-OH | CEF uf | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Stability parameters | Spiked conc.
(µg/ mL) |
0.15 | 40 | 1.2 | 240 | 0.06 | 24 | 1.2 | 240 |
| Benchtop stability in matrix
(room temperature, 8 h) |
Mean of stability
of samples |
0.16 | 39.32 | 1.18 | 230.4 | 0.059 | 24.52 | 1.19 | 253.9 |
| CV % | 3.8 | 1.4 | 4.4 | 2.5 | 1.5 | 3.5 | 2.4 | 1.9 | |
| ST % | 105.8 | 98.3 | 98.1 | 96.0 | 99.5 | 102.2 | 99.8 | 105.8 | |
| Freeze-thaw stability (3
freeze-thaw cycles at -20°C) |
Mean of stability
of samples |
0.14 | 37.40 | 1.15 | 228.6 | 0.058 | 24.18 | 1.12 | 221.3 |
| CV % | 3.2 | 1.8 | 3.4 | 2.7 | 5.1 | 4.1 | 4.4 | 3.1 | |
| ST % | 96.1 | 93.5 | 95.8 | 95.3 | 97.2 | 100.7 | 93.0 | 92.2 | |
| Auto-sampler stability
(24 h at 18°C) |
Mean of stability
of samples |
0.15 | 37.50 | 1.09 | 228.9 | 0.062 | 22.27 | 1.18 | 226.1 |
| CV % | 3.3 | 4.3 | 5.7 | 5.4 | 5.0 | 5.6 | 7.1 | 9.6 | |
| ST % | 101.5 | 93.7 | 90.6 | 95.4 | 103.3 | 92.8 | 98.4 | 94.2 | |
| Long-term stability
(90 days at -20°C) |
Mean of stability
of samples |
0.14 | 37.52 | 1.11 | 217.4 | 0.059 | 22.08 | 1.13 | 221.8 |
| CV % | 6.0 | 4.7 | 4.2 | 7.3 | 1.4 | 5.6 | 3.1 | 5.6 | |
| ST % | 95.2 | 93.8 | 92.2 | 90.6 | 99.1 | 92.0 | 94.4 | 92.4 | |
| Sub-stock solution stability
(28 days at -20°C) |
Nominal Conc.
(µg/ mL) |
50 | 300 | 30 | |||||
| Mean of stability
of samples |
47.89 | 288.39 | 28.63 | ||||||
| CV % | 3.1 | 2.8 | 3.4 | ||||||
| ST % | 95.8 | 96.1 | 95.4 | ||||||