Anti-Xa stability of diluted dalteparin for pediatric use

The low-molecular-weight heparin (LMWH) dalteparin is approved by the Food and Drug Administration for prophylaxis of venous thromboembolism (VTE) in adults and has recently received an indication for acute VTE therapy in adults with cancer. Published reports of experience with dalteparin use in European children suggest that this LMWH agent is safe and effective in the prophylaxis and treatment of VTE in the pediatric population. However, dalteparin is commonly available in the US in a concentrated form that requires dilution for accurate administration in infants and young children.

To investigate the in vitro stability of diluted dalteparin for pediatric use, as measured by serial anti-Xa activity assays over the course of 4 weeks.

At 2 clinical research pharmacies, dalteparin multidose vials (anti-Xa concentration 25,000 U/mL) of the 2 distinct lots presently available for clinical use were diluted 1:10 with preservative-free NaCl 0.9% and maintained in tuberculin syringes at 4 degrees C. Syringes were then sampled for anti-Xa activity by chromogenic assay at baseline and weekly over the course of 4 weeks.

For each lot of dalteparin, there was strong agreement in anti-Xa activity between corresponding diluted syringes prepared at the 2 pharmacy sites. No statistically significant difference in anti-Xa activity was detected from baseline to any time point, nor was a trend of change detected in anti-Xa activity with time for either lot of dalteparin.

These data indicate that the anti-Xa activity of diluted dalteparin for pediatric use is stable over the course of 4 weeks.