[The elimination of hydroxyethyl starch 200/0.5, dextran 40 and oxypolygelatine (author's transl)]

After withdrawal of 400 ml whole blood and subsequent infusion of 500 ml of a colloidal plasma substituent, the intravascular and renal colloid elimination was investigated in 40 test subjects. The individual colloidal solutions could no longer be demonstrated in the intravascular space after the following times: 10% hydroxyethyl starch 200/0.5 (anthrone method) after six weeks, 10% dextran 40 (anthrone method) after two weeks, 6% hydroxyethyl starch 200/0.5 (anthrone method) after four weeks and 5.5% oxypolygelatine (hydroxyproline method) after two days. Colloidal plasma substitutes are polydisperse solutions with various molecular weights and degree of hydroxyethylation and therefore, also have a large number of different elimination constants. With repeated application, the intravascular colloid concentration shifts in favour of the molecules with a longer half life which are difficult to eliminate. The elimination of the clinically employed dextran 40 and oxypolygelatine solution could be best described with an open two-compartment model. As a result of its greater heterogeneity, the elimination of the moderately high molecular weight hydroxyethyl starch 200/0.5 could only be characterized approximately even assuming three elimination constants. In the first four days, the hydroxyethyl starch 200/0.5 was more rapidly eliminated compared to dextran 40. However, subsequently a very much lower elimination from the intravascular space was found for about 3% of the administered hydroxyethyl starch 200/0.5. Oxypolygelatine was eliminated especially rapidly. Accordingly, the greatest renal clearance was found for oxypolygelatine, which showed a close relation to the molecular weight. On the other hand, a rapid elimination simultaneously is followed by a correspondingly lower volume effect.