Related Experiment Video
Updated: Aug 15, 2026

Mapping the Binding Site of an Aptamer on ATP Using MicroScale Thermophoresis
Published on: January 8, 2017
Verapamil plasma binding: relationship to alpha 1-acid glycoprotein and drug efficacy
Abstract:
The relationship between alpha 1-acid glycoprotein (AAG) plasma concentration and plasma verapamil binding was examined in samples obtained 15 minutes after 10 mg IV verapamil to 15 subjects. There was a good correlation (r = 0.83) between the binding ratio and AAG concentration, suggesting that AAG could bind verapamil. This was confirmed in vitro by the addition of AAG to an albumin solution, which resulted in a strong correlation between binding ratio (r = 0.99) and AAG concentration. The relationship between both free and total plasma concentrations and the effects of verapamil on the PR interval was also examined several times after 10 mg IV verapamil in seven of the subjects. While there was a correlation between log of both concentrations and the percent prolongation in PR interval (P less than 0.001), the correlation was stronger with free drug concentration (r2 = 0.58) than with total plasma concentration (r2 = 0.36). The range of free concentrations associated with a given effect (220%) was also narrower than that for total concentration (300%). While these data indicate that AAG is responsible for most of the variability in plasma verapamil binding, which in turn contributes somewhat to variation in effectiveness of a given total plasma concentration, neither of these causes of individual variations is likely to have a major clinical impact in patients who, apart from arrhythmia, are otherwise healthy.
More Related Videos
Related Concept Videos
Drug Distribution: Plasma Protein Binding
Drug Binding to Blood Components
HSA is the most abundant plasma protein and is vital in drug binding. It contains distinct drug-binding sites, with different drugs exhibiting affinity for specific sites. There are three main drug-binding domains for HSA: sites I, II, and III. These domains are further...
Factors Affecting Protein-Drug Binding: Drug-Related Factors
One crucial factor in drug-protein binding is the drug's lipophilicity or its affinity for fat. More lipophilic drugs tend to have higher binding extents. For example, highly lipophilic drugs like cloxacillin exhibit substantial protein binding, with as much as 95% of the drug binding to proteins. In contrast,...
Factors Affecting Protein-Drug Binding: Protein-Related Factors
The physicochemical properties of a drug play a significant role in its ability to bind to proteins. Lipophilic drugs, which dissolve in fats, oils, and lipids, can be bound by...
Factors Affecting Protein-Drug Binding: Patient-Related Factors
Age stands as a key determinant in protein-drug binding. Neonates, characterized by low albumin content, experience heightened concentrations of unbound drugs such as phenytoin and...
Hepatic Drug Clearance: Effect of Protein Binding
For low-extraction-ratio drugs that are less than 80% protein-bound, minor changes in protein binding...

