The properties of the drug usually determine whether the drug is eliminated during the dialysis process or not. These properties include:
1- Water solubility: Hydrophilic drugs are dialyzed more than lipophilic drugs.
2- Molecular weight: Molecules with molecular weight less than 500 can be dialyzed. However drugs with large molecular weight such as protein molecules cannot be dialyzed.
3- Protein binding: Only free (unbound) drug molecules can be dialyzed. Highly bound drug are dialyzed to smaller extent.
4- When the clearance of the drug by the dialysis instrument contribute significantly to the total body clearance of the drug, the plasma drug concentration will decrease significantly due to the dialysis process.