Validation of the anti-factor IIa assay and potency assessment of enoxaparin in pharmaceutical formulations

The low molecular weight heparin enoxaparin sodium is used clinically for the prevention and treatment of venous and arterial thrombosis. An anti-factor IIa assay was applied and validated for the potency evaluation of the pharmaceutical formulations. Investigating the parameters of range, linearity (r2 = 0.9912), precision, accuracy and robustness, the biological assay incorporated a chromogenic end-point and detection at 405 nm. The method yielded good results with a detection limit of 0.01 IU/ml and a quantitation limit of 0.03 IU/ml. Sodium enoxaparin pharmaceutical products were evaluated by the anti-factor Xa assay and the anti-factor IIa assay giving potencies between 97.18% and 106.50%, with an anti-factor Xa/anti-factor IIa ratio between 3.9 and 4.2. The results demonstrated the validity of the anti-factor IIa assay that together with the anti-factor Xa are useful methodologies for the routine quality control of enoxaparin in pharmaceutical products.