Anti-Xa stability of diluted enoxaparin for use in pediatrics.
BACKGROUND
The use of enoxaparin in low-weight pediatric patients is becoming common practice. Anti-Xa stability of unit-dose syringes prepared after dilution beyond one day is presently unknown.


OBJECTIVE
To evaluate the anti-Xa stability of diluted enoxaparin stored in glass vials and tuberculin syringes.


METHODS
Four separate batches of enoxaparin were diluted with sterile water to a final concentration of 20 mg/mL (2000 IU/mL) and aliquoted into plastic 1-mL syringes containing 6 mg (0.3 mL) or maintained in the glass vial. Syringes were stored at room temperature or under refrigeration. The glass vial used for diluting was stored at room temperature. The anti-Xa activity was measured on the date of preparation to 4 weeks. Statistical comparisons determined whether differences in anti-Xa activity in diluted enoxaparin are affected by the storage medium or temperature. A paired t-test was used to determine any significant differences between the anti-Xa activity on date of preparation (baseline) and subsequent time periods, with p < 0.05 considered statistically significant.


RESULTS
The mean baseline anti-Xa activity was 2607 IU/mL (95% CI 2300 to 2914). No measurable decrease occurred in diluted enoxaparin anti-Xa activity in the glass vial maintained over the 4-week period. Compared with the glass vial, room temperature and refrigerated syringe samples had trending decreases of anti-Xa activity at weeks 3 and 4, but did not reach statistical significance.


CONCLUSIONS
A nonsignificant decrease in anti-Xa activity occurred starting at day 22 for the diluted enoxaparin in tuberculin syringes, regardless of storage temperature. Storage up to 4 weeks of diluted enoxaparin in glass or prefilled syringes does not result in a statistically significant loss of anticoagulant potential, as measured by anti-Xa activity.
Department of Pharmaceutical Services, University of California Davis Medical Center, Sacramento, CA 95817-2201, USA. william.dager@ucdmc.ucdavis.edu
William E
WE
Dager
Robert C
RC
Gosselin
Jeffery H
JH
King
Cinda L
CL
Christensen
John T
JT
Owings
Edward C
EC
Larkin
D000925:Anticoagulants / Q000737:chemistry*; D000990:Antithrombin III / Q000037:antagonists & inhibitors* / Q000737:chemistry*; D004355:Drug Stability; D004356:Drug Storage; D017984:Enoxaparin / Q000737:chemistry*; D005898:Glass; D006801:Humans; D007275:Injections, Intravenous; D010372:Pediatrics; D019999:Pharmaceutical Solutions; D010969:Plastics; D013594:Syringes; D013696:Temperature
D000925:Anticoagulants; D017984:Enoxaparin; D019999:Pharmaceutical Solutions; D010969:Plastics; D000990:Antithrombin III