Pharmacology: Albumin is responsible for 70-80% of the colloid osmotic pressure of normal plasma, thus making it useful in regulating the volume of circulating blood. Albumin is also a transport protein and binds naturally occurring, therapeutic and toxic materials in the circulation.
FLEXBUMIN is osmotically equivalent to approximately five times its volume of human plasma. When injected intravenously, 20% and 25% albumin will draw about 3 and 3.5 times, respectively, its volume of additional fluid into the circulation within 15 minutes, except when the patient is markedly dehydrated. This extra fluid reduces hemoconcentration and blood viscosity. The degree and duration of volume expansion depends upon the initial blood volume. With patients treated for diminished blood volume, the effect of infused albumin may persist for many hours; however, in patients with normal volume, the duration will be shorter.
Total body albumin is estimated to be 350 g for a 70 kg man and is distributed throughout the extracellular compartments; more than 60% is located in the extravascular fluid compartment.
The half-life of albumin is 15 to 20 days with a turnover of approximately 15 g per day.
The minimum plasma albumin level necessary to prevent or reverse peripheral edema is unknown. Some investigators recommend that plasma albumin levels be maintained at approximately 2.5 g/dL. This concentration provides a plasma oncotic value of 20 mm Hg.
FLEXBUMIN is manufactured from human plasma by the modified Cohn-Oncley cold ethanol fractionation process, which includes a series of cold-ethanol precipitation, centrifugation and/or filtration steps followed by pasteurization of the final product at 60 ± 0.5°C for 10-11 hours. This process accomplishes both purification of albumin and reduction of viruses.
In vitro studies demonstrate that the manufacturing process for FLEXBUMIN provides for significant viral reduction. These viral reduction studies, summarized in the table, demonstrate viral clearance during the manufacturing process for FLEXBUMIN using human immunodeficiency virus, type 1 (HIV-1) both as a target virus and as model virus for HIV-2 and other lipid-enveloped RNA viruses; bovine viral diarrhea-virus (BVDV), a model for lipid-enveloped RNA viruses, such as hepatitis C virus (HCV); West Nile Virus (WNV), a target virus and model for other similar lipid-enveloped RNA viruses; pseudorabies virus (PRV), a model for other lipid-enveloped DNA viruses such as hepatitis B virus (HBV); mice minute virus (MMV), models for non-enveloped DNA viruses such as human parvovirus B19; hepatitis A virus (HAV), a target virus and a model for other non-enveloped RNA viruses.
These studies indicate that specific steps in the manufacture of FLEXBUMIN are capable of eliminating/inactivating a wide range of relevant and model viruses. Since the mechanism of virus elimination/inactivation by fractionation and by heating is different, the overall manufacturing process of FLEXBUMIN is robust in reducing viral load. (See Table.)
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