Comparative analysis of purity of human albumin preparations for clinical use

Albumin is the most prevalent plasma protein and serves numerous physiological roles, both in body fluid management and in various other capacities. In many diseases, a deficiency of albumin has been observed, and in certain conditions, albumin substitution has been demonstrated to improve outcome in comparison to plasma expansion using crystalloid or other colloid solutions. The favourable effects of using albumin in patients with liver cirrhosis are likely associated with the non-oncotic functions of albumin. Albumin for clinical use is obtained through fractionation of pooled donor plasma. The production procedures are optimized to ensure pure, chemically uncompromised and native protein.

We have extensively analysed commercial preparations of human albumin for clinical use from six different providers. Parameters that must correspond to the requirements of international pharmacopoeias were assessed (aluminium, ethanol, sodium, the presence of dimers and oligomers) and found to conform in all cases. In addition, we used for the first time nuclear magnetic resonance (NMR) as an additional analytical approach for investigating in greater depth the quality of a biological remedy gained from human plasma. We applied both ¹H NMR and ¹³C-HSQC for confirming the identity of the albumin preparations, which also conformed in all cases. Moreover, we utilized T₂-filtered ¹H NMR and ¹³C-HSQC measurements to identify the presence of small molecules in the preparations. This demonstrated similar patterns of additional substances present, but also unveiled certain differences in purity in the products of the different providers.

Our analyses confirmed that albumin preparations in clinical use conform to the requirements. We furthermore demonstrate that NMR measurements can provide further depth in identity and purity measurements of biologicals. Despite largely standardized protocols in pharmaceutical albumin production, our in-depth analyses revealed differences in purity. Some samples exhibited lower levels of components other than albumin. We discuss possible causes of these observations and their potential implications for clinical therapy.