Albumin-purification method comprising a nanofiltration step, solution, and composition for therapeutic use containing the same

Abstract

The invention relates to an albumin-purification method comprising a step consisting in subjecting an aqueous albumin solution, with a concentration of between 15 g / l and 80 g / l and a pH of not less than 7, to nanofiltration in a temperature range of between 15 DEG C. and 55 DEG C. The invention also relates to: a virally-safe aqueous albumin solution which can be obtained using the invention method and in which the sites for the transport and binding of the active therapeutic ingredients of the albumin are available; and an albumin composition for therapeutic use, which is obtained by adapting the albumin solution that is intended for clinical use.

Description

FIELD OF THE INVENTION [0001] The present invention relates to an albumin purification method comprising a nanofiltration step, a solution and a composition for therapeutic use containing the same, obtainable by the method of the invention. BACKGROUND OF THE INVENTION [0002] Albumin is a major protein of human or animal blood plasma. Clinical use of albumin, as an active ingredient, requires its extraction and purification, which is traditionally carried out by known methods, such as those of Cohn et al. (J. Am. Chem. Soc., 68, 459, 1946) and Kistler et al. (Vox Sang., 7, 1962, 414-424) which are additionally applicable to an industrial scale. [0003] Albumin requirements amount to about 100-300 kg per million inhabitants according to country; for that reason, it is necessary, for clinical purposes, to provide an albumin free from pathogenic viruses and contaminants, which are sources of diseases. Thus, as regards transfusion-transmissible viruses, safety is ensured by viral inactiva...

AI Technical Summary

Benefits of technology

[0015] Thus, the Applicant surprisingly found that using a judicious combination of pH, albumin concentration and temperature (and consequently viscosity) values, in the aqueous albumin solution submitted to the nanofiltration step, makes it possible to reach an efficient optimisation of the albumin recovery yield, and rates of reduction of viruses and other undesirable macromolecules higher than the limits set by the control authorities (4 log). It has been brought to light that a nanofiltration carried out under the conditions of the invention makes it possible to filter amounts higher than 5 kg albumin per m2 filter, thus defining the protein load, while optimising the duration of the operation and the filtrate flow rate. The nanofiltered albumin solutions show a very high degree of safety in respect of particulate contaminants with a size of e.g. at least about 13 nm, e.g. viruses such as non-enveloped viruses, prions, albumin polymers (tetramers-decamers) generated during steps of albumin manufacture or during the pasteurisation at 60° C., micelle-like lipopolysaccharides, nucleic acids and aggregated proteins. The aqueous albumin solutions thus obtained. are also an intermediate product capable of being processed into pharmaceutical formulations for clinical use (see further on). DETAILLED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Thus, surprisingly, the Applicant has further found that a decreasing ionic strength is correlated with a better viral reduction.

[0026] Although any albumin may be suitably used as starting material, its origin may be a factor affecting the nanofiltration yield, depending on whether it contains thermal stabilisers or was heat-treated (thermal shock or pasteurisation). Thus, in the method according to the invention, using an albumin obtained by ethanol extraction according to Cohn et al. or Kistler et al. as mentioned above, and purified by ion-exchange or affinity chromatography, can result in an increased albumin recovery and / or a reduced filtration duration.

[0032] The safety achieved with these albumin compositions for therapeutic use makes it possible to suppress the pasteurisation step, a source of drawbacks as mentioned above, and therefore, to add usual protection stabilisers against thermal effects, which also bind on the albumin sites, thus preventing albumin from binding the relevant molecules. The albumin of these compositions according to the invention retains its binding and transport potential of various active ingredients, and through this binding, reduces their toxicity or increases the bioavailability by a depot effect.

Problems solved by technology

Other side effects are related to the presence of albumin polymers occurring during albumin purification and especially during the above-mentioned pasteurisation step.

However, the presence of host cell proteins is often detected and the purification methods must therefore have a very high resolution, which is generally detrimental to the yield.

The production cost of a recombinant albumin may then prove to be too high in comparison to that of an albumin generated from plasma.

This leaves chance for viruses to pass through due to the manufacturing imprecision of filtration membranes.

Moreover, filter clogging occurs in front operation, resulting in a blockage of the filtrate flow.

Actually, during the nanofiltration process, the large-sized solutes accumulate on the filter, which slows down the filtrate flow until the filter is completely clogged.

The technical solutions to this clogging which consist of implementing a tangential flow nanofiltration, increasing the pressure and changing the directions of the flows do not prove to be efficient because the clogging is progressive and irreversible.

An industrial development is therefore greatly compromised because it requires the use of very numerous filters and very large volumes of solutions to be filtered, which generates a prohibitive cost and abnormally increased manufacturing times.

307-350, 1974, show that the effect of each parameter can individually result in increased or decreased efficiency of virus retention and recovery yield of solutes, and that combining several parameters does not systematically favour a synergy of the effects of improvement of the filtration conditions.

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