Bilirubin and alkaline phosphatase clearance from blood-plasma by perfusion through activated carbon

The Adsorption of Bilirubin from Aqueous Solution onto Solid Cholestyramine and Polyvinylpyrrolidone

Shifts in the visible spectrum of aqueous bilirubin (BR) resulting from the addition of soluble polyvinylpyrrolidone (PVP) suggest specific interactions. Hence, isotherms were determined for the adsorption of BR from aqueous solution onto solid, cross-linked PVP and onto cholestyramine (CA) (used as a reference adsorbent) at 0, 10, 20 and 25°C. Although adsorption onto PVP reaches equilibrium values more rapidly than for CA, the latter adsorbent has a larger capacity. Furthermore the isotherms for PVP are independent of temperature while those for CA show an increase in BR adsorbed with an increase in temperature.

[In vitro evaluation of adsorbents used in haemoperfusion (author's transl)]

The properties of six adsorbents for Haemoperfusion were investigated in vitro: Amberlite XAD-2; Amberlite XAD-4; Haemocol; collodion coated charcoal; albumine-collodion encapsulated charcoal and activated carbon fibers. Carbromal and diazepam are most quickly removed from aqueous solutions by Amberlite XAD-2 and XAD-4. Of the charcoal containing materials, Haemocol eliminates most rapidly carbromal and diazepam; while activated carbon fibers remove phenobarbital faster. When heparinized blood is perfused, a remarkable reduction in platelet count is observed. The drop is most pronounced with Amberlite XAD-2 and XAD-4, but even when using charcoal preparations the platelet depletion can reach 10% of the original number over 5 hours. Haemolysis is most pronounced with Amberlite XAD-2, XAD-4 and Haemocol. As the efficiency of the adsorbents towards the various drugs differ and as their adverse effects also vary, the decision for a particular material will have to be made according to the individual case.

Removing substances from blood by affinity chromatography. II. Removing bilirubin from the blood of jaundiced rats by hemoperfusion over albumin-conjugated agarose beads

In vitro studies indicate that bilirubin and other albumin-bound substances can be efficiently removed from plasma by filtration over albumin-conjugated agarose beads. The effectiveness of this technique in vivo was investigated in rats by using a closed extracorporeal hemoperfusion system. Five Gunn rats whose endogenous bilirubin pool had been labeled with [(3)H]bilirubin and five Sprague Dawley rats with surgically created biliary obstruction were chosen as models of unconjugated and conjugated hyperbilirubinemia. Indocyanine green was injected into rats and its removal also studied. In the Gunn rats, 98% of the bilirubin was removed from plasma during the initial pass over the column as determined isotopically and chemically. Plasma bilirubin levels fell more than 70% from 8.2+/-1.6 mg/100 ml (mean+/-SD) to 2.6+/-0.5 mg/100 ml during a 1-h hemoperfusion. An average of 1,061 mug of bilirubin was recovered from the columns, representing 22.5+/-4.2% of the total exchangeable bilirubin pool and 96+/-36.4% of the plasma pool. Results were similar in the rats with biliary obstruction and in those given indocyanine green. Normal Sprague Dawley rats experience minimal changes in formed blood elements, electrolytes, and proteins as the result of hemoperfusion. When the total volume of the column did not exceed 51% of the estimated blood volume of the animal, the survival rate was 100% in 20 studies, and the procedure was without observable ill effect. Extrapolation of both in vitro and in vivo data to man suggests that extracorporeal hemoperfusion over albumin-agarose columns may be a practical means of assisting hepatic excretory function.

Removing substances from blood by affinity chromatography. I. Removing bilirubin and other albumin-bound substances from plasma and blood with albumin-conjugated agarose beads

Substances such as bilirubin that bind tightly to plasma proteins cannot readily be removed from blood. We describe here the use of affinity chromatography as a new approach to the removal of proteinbound metabolites and toxins from blood. Agarose beads were coupled via cyanogen bromide to human serum albumin so as to contain 30-50 mg of albumin/g wet wt. Such beads, when exposed to plasma from a patient with congenital nonhemolytic jaundice labeled with [(14)C]-bilirubin, bound more than 150 mug bilirubin/g of beads. The binding was saturable, concentration-dependent, relatively independent of flow rate, and reversible by elution with plasma, albumin, or 50% (vol/vol) ethanol. The beads could be repeatedly reused without loss of efficiency after ethanol elution and long storage in the cold. Salicylate, cortisol, and taurocholate, which bind weakly to albumin, were retarded by the beads but eluted with neutral buffer. Thyroxine, taurolithocholate, chenodeoxycholate, and digitoxin bound tightly but were eluted with 50% ethanol. Digoxin did not bind at all. When whole blood was passed over agarose-albumin beads, bilirubin was removed, calcium and magnesium fell slightly, but red cells, white cells, platelets, clotting factors, and a variety of electrolytes and proteins were substantially unchanged. Agarose-albumin beads may be useful for removing protein-bound substances from the blood of patients with liver failure, intoxication with protein-bound drugs, or specific metabolic deficits. Furthermore, it may be possible to make useful adsorbents by attaching other proteins to agarose or other polymer beads.