Table 1.
Adsorbents evaluated for their characteristics to remove caprylate and NAT from HSA.
Fig 1.
Schematic illustration of the batch tests and the dynamic model.
The batch tests were performed with 10% (w/v) adsorbent in 20% HSA solution for 24 hours to determine the adsorption capacity of NAT and caprylate of each adsorbent. The dynamic model was used to simulate the removal rates of stabilizers from HSA solution before intravenous administration into the patient. 50 ml 20% HSA solution was pumped (0.5 ml/min) through a 5 ml adsorbent cartridge and 1 ml HSA fractions were collected post cartridge for determination of the NAT, caprylate level and ABiC.
Fig 2.
Setup of the dialysis circuit to determine the removal of the stabilizers by a high flux dialyser.
200 ml 5% HSA solution was dialysed against 0.9% NaCl solution using a pediatric high flux dialyser. Flow rates for the HSA solution was 100 ml/min and the dialysate flow was set to 50 ml/min. Samples were taken during 4 hours treatment time.
Table 2.
The maximum time [h] to reach the equilibrium concentration for caprylate and NAT removal and adsorption capacity [mg/g] for caprylate and NAT of each adsorbent in the batch tests.
Fig 3.
Percental removal rates of caprylate, N-acetyltryptophanate and of both from 20% HSA infusion solution by different adsorbents tested in batch.
HSA solution was incubated with 10% (v/v) adsorbent for 24 hrs at 37°C. Samples for NAT and caprylate quantification were taken after 30, 60, 120, 240, 360 min and 24 hrs. The stabilizer levels of HSA solution without adsorbent (dotted line) were set to 100%. The caprylate and NAT levels of stabilizer free lyophilized HSA act as negative control (dashed lines).
Fig 4.
The adsorbent treatment increases the ABiC II levels.
The albumin binding capacity (ABiC II) after adsorbent treatment was compared to untreated HSA and HSA without stabilizers, which was set to 100% (A). All adsorbent treatments caused a significant (p ≤ 0.05) increase of ABiC II. The albumin concentration was measured after 24 hours adsorbent treatment in batch to calculate the albumin binding in mg per ml adsorbent volume (B).
Table 3.
Calculated outer adsorbent surface of an 5 ml filled cartridge, assuming that all adsorbent are spherical particles and follows the close-packing of equal spheres (adsorbent volume = 74% of cartridge volume).
Table 4.
ABiC II values compared to HSA without stabilizer in percent and removal rates of caprylate, N-acetyltryptophan and both in percent from a 20% HSA solution using different adsorbent in the dynamic model.
Fig 5.
Pre cartridge concentrations of stabilizers from 20% HSA solution using different adsorbents in the dynamic model.
50 ml 20% HSA solution was pumped with 0.5 ml/min through a 5 ml adsorbent filled cartridge. 1 ml fractions were collected post cartridge for NAT and caprylate measurement.
Fig 6.
ABiC II levels of the post cartridge fractions from the dynamic model.
ABiC II was determined from post adsorbent cartridges fractions. ABiC II of HSA without stabilizer (dotted line) was set to 100%. ABiC II of untreated HSA is shown in broken line.
Fig 7.
Removal of stabilizers during 4 hours dialysis.
200 ml 5% HSA solution was dialyzed against physiological sodium chloride solution using a pediatric high-flux dialyzer. The flow rate of the HSA solution was 100 ml/min and the dialysate flow was set to 50 ml/min. The treatment time was 4 hours and samples were taken after 30, 60, 120, 180 and 240 min, n = 4.
Table 5.
Calculated clearance rates using the formula (1) for NAT and caprylate from the dialysis experiment (n = 4).