Theophylline protein binding

Area of Science:

• Pharmacology
• Biochemistry
• Clinical Chemistry

Background:

• Theophylline is a widely used medication for respiratory diseases.
• Understanding drug-protein interactions is crucial for pharmacokinetics.
• Human serum albumin is a primary drug-binding protein.

Purpose of the Study:

• To investigate the binding characteristics of theophylline to human serum albumin and plasma.
• To quantify theophylline-protein binding in healthy individuals and asthmatic patients.

Main Methods:

• Equilibrium dialysis was employed to study theophylline binding at 22°C and pH 7.4.
• Scatchard analysis was used to determine binding parameters (N1, K1, N2, K2).
• Theophylline protein binding percentages were measured in patient and volunteer serum samples.

Main Results:

• Theophylline exhibited similar binding parameters for human serum albumin and plasma, suggesting albumin as the primary binding site.
• Binding parameters for albumin: N1 = 1.8, K1 = 2.6 x 10³ L/mol; N2 = 6.0, K2 = 7 x 10² L/mol.
• Theophylline binding was slightly but significantly higher in asthmatic patients (37.5 ± 0.4%) compared to healthy volunteers (35.5 ± 0.3%).

Conclusions:

• Theophylline predominantly interacts with the albumin fraction in human plasma proteins.
• Slightly increased theophylline binding in asthmatic patients warrants further investigation.
• Standardized experimental conditions led to low intersubject variability in binding measurements.