Equilibrium Dialysis
Equilibrium Dialysis - Related Videos
03:00
Measuring Drug Binding to Caseum from Tuberculosis Lesions via the Rapid Equilibrium Dialysis Method
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2025
Source: Sarathy, J. P. et al. An In Vitro Caseum Binding Assay that Predicts Drug Penetration in Tuberculosis Lesions. J. Vis. Exp. (2017)This video demonstrates an in vitro assay for measuring drug binding to caseum from tuberculosis lesions using rapid equilibrium dialysis. It outlines the steps for preparing caseum suspensions, performing dialysis, and calculating the unbound drug fraction to predict drug penetration into caseum.
05:26
Dialysis: Diffusion Based Separation
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2023
Dialysis is a common technique used in biochemistry for separating molecules based on diffusion. In this procedure, a semipermeable membrane allows the movement of certain molecules based on size. This method can be applied to the removal of buffer, known as desalting, or exchanging buffer molecules or ions from a protein solution. This video covers the principles of dialysis along with a general procedure. Several applications of dialysis are reviewed, including the removal of gradient...
01:15
Dialysis
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2024
Dialysis is a diffusion-based purification process that separates analyte molecules from a complex matrix. This is accomplished by allowing molecules in the solution to pass through a semipermeable membrane into a liquid on the other side. The membrane is usually made of cellulose acetate or cellulose nitrate, and the second liquid must be miscible with the solution. Ions (e.g., chloride or sodium) or organic molecules (e.g., glucose) can pass through the membrane pores, which generally have...
01:27
Dialysis
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2024
Renal failure occurs when the kidneys lose their ability to filter waste products from the blood effectively. It can be classified into two types: acute renal failure (ARF) and chronic renal failure (CRF). Acute kidney injury develops suddenly and can be caused by pre-renal causes (e.g., hypovolemia, shock), intrinsic renal causes (e.g., acute tubular necrosis), or post-renal causes (e.g., urinary obstruction). In contrast, chronic renal failure progresses gradually over time and is often...
02:20
Dynamic Equilibrium
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2020
A reversible chemical reaction represents a chemical process that proceeds in both forward (left to right) and reverse (right to left) directions. When the rates of the forward and reverse reactions are equal, the concentrations of the reactant and product species remain constant over time and the system is at equilibrium. A special double arrow is used to emphasize the reversible nature of the reaction. The relative concentrations of reactants and products in equilibrium systems vary greatly;...
FAQs
The membrane separates the protein-containing compartment from the protein-free compartment without preventing movement of small, unbound drug molecules. Protein-bound drug remains with the macromolecule, whereas free drug can redistribute between chambers. This selective permeability makes the final concentration difference interpretable as a measure of the drug’s free and protein-bound fractions.
After diffusion has reached equilibrium, the freely mobile drug distributes between the two chambers, while the protein-associated fraction remains in the protein-containing side. Comparing drug concentrations across the chambers therefore indicates how much is unbound versus retained through protein binding. A larger bound fraction corresponds to stronger association with the macromolecule under the tested conditions.
If another compound competes for protein-binding sites, it can change the amount of drug associated with the macromolecule and consequently change the free fraction measured after equilibrium. This matters clinically because altered binding can modify drug availability. Equilibrium Dialysis can therefore help identify potential displacement interactions and characterize how binding changes in combined-compound settings.
A protein-containing sample and a comparison compartment are separated by a semipermeable membrane, then maintained until small unbound molecules diffuse and the system reaches equilibrium. Investigators measure the drug concentration on the relevant sides and use the resulting difference to estimate free and protein-bound fractions. The membrane must retain the protein while permitting small solutes to move.
The method is useful when researchers need to characterize protein binding as part of drug distribution, pharmacokinetics, or dose-response investigations. Its measurements help distinguish the fraction available in an unbound form from the fraction associated with plasma proteins. That information can clarify how binding behavior relates to drug availability across clinical research questions.
Equilibrium Dialysis provides binding information that can complement measured drug concentrations during therapeutic drug monitoring. Knowing the free and protein-bound fractions helps researchers interpret how much drug may be available relative to the total measured amount. The same data can clarify pharmacokinetic behavior, distribution patterns, and the possible clinical significance of changes in protein binding.