Table 2.
Stability of Cefazolin during Storage in Accufuser Elastomeric Infusion Device, Expressed as Percentage of Original Concentration Remaining (Mean ± SD)*
| Study Day |
Nominal 5 mg/mL |
Nominal 40 mg/mL |
||||||
|---|---|---|---|---|---|---|---|---|
|
D5W |
NS |
D5W |
NS |
|||||
| 23°C | 4°C | 23°C | 4°C | 23°C | 4°C | 23°C | 4°C | |
| Observed initial concentration (mg/L) | 4.76 ± 0.14 | 4.57 ± 0.07 | 4.85 ± 0.32 | 4.64 ± 0.13 | 32.55 ± 1.32 | 33.06 ± 1.64 | 31.74 ± 0.95 | 33.49 ± 3.54 |
| 1 | 98.8 ± 0.4 | 102.0 ± 0.8 | 96.3 ± 2.6 | 102.2 ± 1.3 | 97.2 ± 0.9 | 100.3 ± 1.2 | 102.0 ± 2.4 | 100.9 ± 1.5 |
| 2 | 95.1 ± 2.1 | 102.0 ± 1.0 | 95.7 ± 2.3 | 101.4 ± 2.5 | 93.7 ± 0.8 | 95.5 ± 0.8 | 97.1 ± 1.7 | 98.4 ± 0.4 |
| 7 | 91.0 ± 1.0 | 99.7 ± 1.3 | 91.3 ± 3.0 | 100.5 ± 2.4 | 93.1 ± 0.9 | 97.3 ± 2.0 | 94.2 ± 2.7 | 99.0 ± 2.0 |
| 11 | 98.9 ± 0.7 | 99.0 ± 2.4 | 97.7 ± 1.9 | 96.5 ± 0.6 | ||||
| 14 | 99.7 ± 1.1 | 98.8 ± 1.0 | 97.7 ± 2.8 | 97.9 ± 0.8 | ||||
| 18 | 99.6 ± 0.6 | 99.8 ± 1.9 | 99.1 ± 1.2 | 99.1 ± 1.2 | ||||
| 28 | 95.1 ± 0.5 | 96.2 ± 1.8 | 95.1 ± 1.4 | 94.0 ± 1.0 | ||||
| Degradation rate† (%/day) | −1.256 | −0.194 | −1.082 | −0.164 | −0.808 | −0.097 | −0.957 | −0.179 |
| T–90% (days)‡ | 7.45 | 59.79 | 7.90 | 69.60 | 9.93 | 90.67 | 11.20 | 56.03 |
| Fastest degradation rate§ | ||||||||
| Lower limit of 95% CI (%/day) | –2.409 | –0.306 | –2.204 | –0.257 | –2.745 | –0.268 | –2.626 | –0.314 |
| T–90% (days) | 4.15 | 32.64 | 4.54 | 38.97 | 3.64 | 37.36 | 3.81 | 31.89 |
| Estimated % remaining with storage ¶ | ||||||||
| 13.5 days at 4°C + 12 h at 23°C | 94.66 | 95.43 | 95.01 | 94.43 | ||||
| 27.5 days at 4°C + 8 h at 23°C | 90.37 | 91.84 | 91.27 | 90.06 | ||||
CI = confidence interval, D5W = dextrose 5% in water, NS = normal saline (0.9% sodium chloride), SD = standard deviation.
Each value was based on duplicate determination of 3 samples. The percent remaining was based on the observed concentration on day 0 (100%).
The degradation rate was determined by linear regression of the percent remaining on each study day.
T–90% is the time for the concentration to decline by 10% (i.e., time to reach 90% of initial concentration), as determined from the degradation rate.
Fastest degradation rate and T–90% were based on the lower 95% confidence limit of the regression-determined slope.
Using the fastest observed degradation rates determined by regression (95% CI), calculations were completed for a solution stored in an Accufuser elastomeric infusion device for 13.5 or 27.5 days, followed by storage for an additional period at room temperature (23ºC).