Table 5.
Stability of Clindamycin during Storage in Accufuser Elastomeric Infusion Device, Expressed as Percentage of Original Concentration Remaining (Mean ± SD)*
| Study Day |
Nominal 1 mg/mL |
Nominal 12 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) | 0.72 ± 0.05 | 0.76 ± 0.06 | 0.77 ± 0.11 | 0.76 ± 0.09 | 9.24 ± 0.93 | 8.77± 0.28 | 8.92 ± 0.04 | 9.62 ± 0.49 |
| 1 | 104.0 ± 1.9 | 102.6 ± 2.8 | 102.8 ± 1.7 | 103.2 ± 1.9 | 102.8 ± 2.9 | 101.4 ± 2.8 | 102.4 ± 2.6 | 101.8 ± 4.8 |
| 2 | 102.7 ± 1.4 | 102.0 ± 2.1 | 101.8 ± 1.2 | 102.3 ± 1.3 | 102.2 ± 2.8 | 104.1 ± 1.5 | 100.6 ± 0.9 | 100.2 ± 2.8 |
| 7 | 104.9 ± 1.4 | 104.6 ± 2.1 | 104.1 ± 1.7 | 103.9 ± 2.0 | 100.9 ± 2.9 | 100.2 ± 3.3 | 99.4 ± 0.6 | 99.2 ± 4.8 |
| 14 | 104.3 ± 3.1 | 104.5 ± 0.7 | 101.2 ± 2.4 | 100.7 ± 3.4 | ||||
| 21 | 103.0 ± 1.6 | 103.7 ± 1.5 | 99.0 ± 1.1 | 99.1 ± 5.3 | ||||
| Degradation rate† (%/day) | 0.501 | 0.108 | 0.465 | 0.127 | –0.043 | –0.107 | –0.230 | –0.055 |
| T–90% (days)‡ | 23.2 | 110.3 | 23.7 | 94.2 | 269.6 | 110.2 | 48.4 | 193.3 |
| Fastest degradation rate§ | ||||||||
| Lower limit of 95% CI (%/day) | 0.891 | 0.121 | 0.469 | 0.076 | 1.274 | 0.360 | 0.230 | 0.198 |
| T–90% (days) | 11.2 | 82.9 | 21.3 | 132.3 | 7.8 | 27.8 | 43.4 | 50.4 |
| Estimated % remaining with storage¶ | ||||||||
| 13 days at 4°C + 24 h at 23°C | 97.5 | 98.5 | 94.0 | 97.2 | ||||
| 21 days at 4°C + 24 h at 23°C | 96.6 | 97.9 | 91.2 | 95.6 | ||||
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 or 21 days, followed by storage for an additional period at room temperature (23ºC).