Albumin

• Ph. Eur.Human Albumin Solution
• USP–NFAlbumin Human

Albuminar; Albutein; Buminate; human serum albumin; HSA; Plasbumin; normal serum albumin

Albumin (human serum) · [—]

Polymer, mixture or material of variable composition — no single molecular formula applies.

Stabiliser, lyoprotectant

Typical concentrations: — · Dosage forms: Sterile (parenteral/ophthalmic)

As an excipient, albumin is used mainly in parenteral products to stabilise proteins and other labile actives (for example in vaccines, interferons, erythropoietin and botulinum toxin products), to reduce adsorption of low-concentration proteins to container surfaces, and as a cryoprotectant in freeze-dried products. Excipient levels are low, well below the 4–25% used therapeutically. Albumin microspheres and nanoparticles are also used as drug carriers (for example albumin-bound paclitaxel).

Human albumin solution is a clear, slightly viscous liquid that is almost colourless, yellow, amber or green-tinged. The dried protein is a white to yellowish powder or flakes. Albumin is the main protein of human plasma.

Protein content

solutions are typically 4–5% (iso-oncotic) or 20–25% (concentrated)

pH

about 6.4–7.4

Isoelectric point

≈ 4.7–4.9

Structure

single non-glycosylated polypeptide chain of 585 amino acids

Solubility

freely soluble in water and dilute salt solutions; precipitated by high concentrations of ethanol and by heavy-metal salts

Albumin solutions are heat-treated during manufacture and are stable for several years when stored as directed, usually below 30 °C and protected from light; they must not be frozen. Solutions contain no antimicrobial preservative, so once opened the container should be used promptly, and turbid solutions or those with deposits should not be used.

Precipitated or denatured by ethanol at high concentrations, heavy-metal salts, strong acids and alkalis and excessive heat. Mixing with protein hydrolysates, amino acid solutions or solutions containing alcohol should be avoided. Albumin binds many drugs, which can alter their free fraction.

Obtained from pooled human plasma by cold ethanol fractionation (the Cohn process or its modifications). Sodium caprylate and/or N-acetyltryptophan are added as stabilisers and the solution is heated at 60 °C for 10 hours to inactivate viruses. Recombinant human albumin produced in yeast is also available.

Albumin is a normal body protein and is generally well tolerated; hypersensitivity reactions are rare. Because it is derived from human plasma, donor screening, testing and viral inactivation are used to minimise the risk of transmitting infectious agents. At therapeutic doses it can cause circulatory overload in susceptible patients.

Handle aseptically using the precautions normally applied to blood products. Gloves and eye protection are recommended.

Included in the FDA Inactive Ingredient Database (parenteral preparations). Plasma-derived albumin is regulated as a biological product, and its use as an excipient must be justified and documented in licensed medicines.

Recombinant human albumin; bovine serum albumin (used in diagnostics and cell culture, not in human medicines); gelatin.

Because of the theoretical risk of transmitting infectious agents and supply concerns, newer protein formulations tend to replace plasma-derived albumin with recombinant albumin or with non-protein stabilisers such as polysorbates, sugars and amino acids.