Human albumin : benefits
Human albumin : indications and clinical benefits
The package inserts of albumin solutions in Europe follow the Summary Product Characteristics developed by the European Medicines Agency and endorsed by the national health authorities . It is currently being reviewed by the European health authorities whose approval is scheduled for 2013
Christian J Wiedermann MD FACP Associate Professor of Internal Medicine , Medical University of Innsbruck , Director , Department of Internal Medicine , Central Hospital of Bolzano , Italy Email : christian . wiedermann @ asbz . it
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Albumin is the most abundant plasma protein in the human body , alone constituting about 55 % of the total protein content of plasma . It is formed by a single polypeptide chain of 585 amino acids with a molecular weight of 66,500 Dalton , synthesised entirely by the liver . Of the total content of albumin ( about 250 – 350g for a healthy 70kg adult ), approximately 42 % is located in the intravascular compartment , and its half-life is about 20 days . 1
Albumin is a multifunctional protein with both colloidal and pharmacological activity . The exchange of fluids between the intravascular and extravascular compartments is basically governed by the levels of hydrostatic and oncotic pressure and the degree of capillary membrane permeability . Albumin ’ s colloidal activity is essential in maintaining fluid balance between the intravascular and interstitial compartments . Because it is the predominant plasma protein , albumin accounts for approximately 75 – 80 % of plasma colloid osmotic pressure ( COP ). Due to the presence of several histidine residues with an acid dissociation constant very similar to the plasma pH , albumin is an excellent buffer in plasma as well as the main extravascular buffer able to donate positive and negative charges in case of alkalosis and acidosis , respectively ( see Box 1 ). In addition , albumin is endowed with diverse biologically specific capabilities such as ligand binding ,
" Human albumin may be preferentially used in cases where a sustained action on the blood volume is required or when there is a contraindication for non-protein colloids ”
antioxidant , free radical-scavenging and anti-inflammatory activity , inhibition of apoptosis and cell signalling . 1
Albumin specifically binds to a wide array of endogenous ligands , including metabolites , lipids , hormones , metal ions and high-affinity endothelial cell albumin receptors . 2 Ligand binding itself may serve multiple purposes such as transport , sequestration and transcytosis . Additionally , albumin binds numerous administered drugs and in many cases can modify their bioavailability and pharmacokinetics . 3 For example , albumin administration results in increased effects of loop diuretics by augmenting drug delivery to the renal tubule . 4 Evidence concerning these non-oncotic pharmacological properties of albumin continues to accumulate rapidly . Albumin plays a modulating role in haemostasis due to binding between sulfhydryl groups of albumin and nitric oxide ( NO ), thus slowing the inactivation of NO , which exhibits anti-aggregating effects on platelets and has vasodilator properties . 5 Albumin contributes to the maintenance of normal permeability of capillaries to www . hospitalpharmacyeurope . com