A Comparative In Vitro Study of the Anticoagulant Effects of Branded versus Biosimilar Preparations of Enoxaparin

Several biosimilars of the low-molecular-weight heparin enoxaparin are available on the market, but no studies have compared the effects of branded versus biosimilar enoxaparin on coagulation assays. The aim of this study was to compare the in vitro anticoagulant effects of the branded enoxaparin (Clexane) and three biosimilar versions (Critinox, Inhixa, and Qnox) on a panel of coagulation assays. A platelet-poor plasma pool was spiked with five concentrations of four different enoxaparins (range 0.2–2.0 IU/mL). These were measured using the chromogenic anti-Xa assay and chromogenic anti-IIa assay. The following coagulation assays were performed in duplicates for each enoxaparin preparation: prothrombin time (PT), activated partial thromboplastin time (aPTT), PT-derived fibrinogen, Clauss fibrinogen, thrombin time (TT), dilute Russell's viper venom time (dRVVT) screen and confirm, one-stage factors VII, VIII, and IX, and chromogenic assays for factors VIII and IX. Positive correlations were observed between increasing concentrations of the different enoxaparins and PT, aPTT, TT, and dRVVT screen and confirm. Negative correlations were observed with all one-stage factor assays and chromogenic FVIII. No consistent correlation was observed for the fibrinogen assays and chromogenic FIX. All enoxaparin preparations had an estimated mean anti-Xa:anti-IIa activity ratio between 3.12:1 and 3.92:1. There were no statistically significant differences between the four preparations of enoxaparin. This study showed that branded and biosimilar versions of enoxaparin exhibited very similar in vitro anticoagulant effects across the coagulation assay panel tested.