7.21 : Physiological Pharmacokinetic Models: Assumption with Protein Binding

Physiological models with protein binding in pharmacokinetics offer a sophisticated approach to understanding drug disposition. These models consider drug-protein interactions, enabling them to effectively predict drug concentrations in different organs and tissues. This precision aids in accurate drug dosing, providing a significant advantage over conventional models. A key process within these models is equilibration, which ensures that drug concentrations achieve a steady state within the body over time. Calculating the free drug concentration in target organs involves a formula that factors in blood flow rate and the extent of drug binding to proteins.

Models of linear drug binding assume the unbound drug fraction remains constant, irrespective of the total drug concentration. This assumption simplifies the interpretation and application of the model. The term 'Cl_int' denotes an organ's efficiency in drug clearance. It represents the organ's inherent capacity to metabolize and eliminate drugs, a critical factor in drug distribution and effect.

Lastly, the mass balance for the drug in the blood pool provides a comprehensive analysis of drug distribution in all organs. It is an integral part of these models, highlighting the vital role of drug binding in the overall distribution process. Understanding these elements offers valuable insights into drug behavior within the body and contributes to more effective and precise drug administration.