Collaborative study for the establishment of replacement batches of Ph. Eur. Heparin Low-Molecular-Mass for Calibration CRS.

An international collaborative study was run within the framework of the Biological Standardisation Programme (BSP) of the Council of Europe and the Commission of the European Union to establish replacement batches for European Pharmacopoeia (Ph. Eur.) Heparin Low-Molecular-Mass (LMM) for calibration Chemical Reference Substance batch 3 (CRS3) used for the characterisation of LMM heparins by high performance size-exclusion chromatography. Two candidate batches (A, cCRS4 and B, cCRS5) were filled using the same material as the existing official calibrants, adopted with either an assigned number-average molecular mass (Mna) or a broad standard table (BST). Fifteen laboratories evaluated the suitability of these candidate batches for use as calibrants with the pharmacopoeial dual refractive index/ultraviolet (RI/UV) detector calibration method, as well as with a modified mobile phase and the BST calibration method. Seven preparations of LMM heparin were tested. The results confirmed that the proposed batches are suitable for use with the same characteristic Mna as CRS3 and with the BST established for the World Health Organization (WHO) 2nd International Standard (IS). The BST calibration method gave comparable results to the RI/UV method, while showing better reproducibility, being easier to perform and requiring no calibrant with UV absorbance. The modified mobile phase had no impact on the calculated values while improving separation between the calibrant and salt peaks. The two candidate batches were adopted as Ph. Eur. Heparin LMM for calibration CRS batches 4 and 5, respectively, with the assigned Mna value of 3800 and a BST. In anticipation of the depletion of the calibrant required for use with the RI/UV method, and taking into account the unlikely procurement of a new lot of suitable starting material, it was recommended to include the BST method in Ph. Eur. monograph 0828, Heparins, low-molecular-mass . In order to improve peak separation, it was also recommended to include the use of ammonium acetate solution as mobile phase in the monograph, both for the Ph. Eur. RI/UV and the proposed BST calibration methods. Further to this study, Ph. Eur. monograph 0828 was revised to replace the RI/UV method by the BST method. This contributed to the harmonisation of methods across regions, thereby facilitating a concerted global action for the development and establishment of the next batches of calibrants for the quality control of LMM heparins.