Question

The extent to which drugs are removed from the body during hemodialysis therapy is impaired by all but which one of the following? 1. Binding to plasma proteins 2. Drug partitioning from plasma into erythrocytes 3. Large drug distribution volume 4. Slow blood flow through the dialyzer 5. Molecular weight of the drug greater than 6,000 daltons

Answer 1

The extent to which drugs are removed from the body by dialysis is determined primarily by several chemical factors of the drug and also determined by the technical aspects of dialysis.

1. Binding to plasma proteins:

The drug dialyzability is based on the flow of free drug across the dialysis membrane. The drug with high protein binding may decrease the uremic serum because of small plasma concentration which increases the free drug dialyzability. The peritoneal membrane does not allow the protein passage across the dialysis due to large protein-binding complex.

2.Drug partitioning from plasma into erythrocytes:

Tissue Compartmentalization is responsible for drug partitioning into erythrocytes. During dialysis, the ultrafiltration increases the hematocrit level. Increased Drug partition may reduce the clearance. Thus the drug partition into erythrocytes may reduce the total dialytic clearance in the hemoconcentrated states.

3. Large drug distribution volume:

The drug with the high degree of lipid solubility and low plasma protein binding will distribute widely. The large volume of distribution of the drug throughout the tissues will be less likely dialyzed.

4. Slow blood flow through the dialyzer:

Usually, the drug flow through the blood during dialysis. The dialyzability may depend on the flow rates of blood and dialysate. The decreased blood flow rate will result in the decreased amount of drug delivered across the dialysis membrane. The decrease in blood flow rate will increase the drug concentrations due to the slow movement of the drug across the membrane.

5. The molecular weight of the drug greater than 6,000 daltons:

The dialysis is depended upon the size and pores of the dialytic membrane. The small molecular weight membrane will pass more easily through the membrane than the larger molecular weight. Molecular weight greater than 6000 daltons increases hemodiafiltration by 24%.

So, The extent to which drugs are removed from the body during hemodialysis therapy is impaired more by slow blood flow dialyzer.