Linear relationships between plasma binding and lipophilicity of disopyramide derivatives

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Drug Binding to Blood Components01:30

Drug Binding to Blood Components

When drugs enter systemic circulation, they interact with various components of the blood, including proteins such as human serum albumin (HSA), α1-acid glycoprotein (AAG), lipoproteins, globulins, and red blood cells (RBCs).
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...
Pharmacokinetic–Pharmacodynamic Relationship: Duration of Dose-Effect Relationship01:14

Pharmacokinetic–Pharmacodynamic Relationship: Duration of Dose-Effect Relationship

For drugs producing a quantal response, onset occurs when plasma concentration reaches a minimum effective level (Cmin). The drug's action duration depends on how long the plasma concentration remains above Cmin.Two primary factors influence this duration: dose size and the rate of drug removal from the action site. Both depend on the drug's redistribution to poorly perfused tissues and elimination processes. A larger dose promotes rapid onset and prolongs the effect's duration.Consider a...
Pharmacokinetic–Pharmacodynamic Relationship: Intensity of Dose-Effect Relationship01:23

Pharmacokinetic–Pharmacodynamic Relationship: Intensity of Dose-Effect Relationship

Pharmacodynamics explores the relationship between drug concentration and its effect. In a quantal response drug, the duration of action better correlates with drug concentration, while for graded effect drugs, the intensity of response is more relevant. This intensity depends on the dose, drug removal rate, and the region of the concentration–response curve.The concentration–response curve can be divided into three regions. Region 3 (80–100% maximum response) demonstrates that even as drug...
Pharmacokinetic–Pharmacodynamic Relationship: Problems01:24

Pharmacokinetic–Pharmacodynamic Relationship: Problems

The empirical approach to drug therapy optimization relies on correlating pharmacological response with administered dosage. Such an approach can be costly, time-consuming, and often yields poor correlation due to variables like formulation factors and drug elimination characteristics. A more precise approach correlates response with plasma drug concentration or the amount of drug in the body, rather than dosage. This is achieved through pharmacokinetic-pharmacodynamic (PK/PD) modeling, which...
Pharmacodynamic Models: Linear Concentration–Effect Model01:15

Pharmacodynamic Models: Linear Concentration–Effect Model

The linear concentration–effect model, underpinned by the principle that pharmacological effect (E) is directly proportional to plasma drug concentration (C), emerges as a pivotal simplification of the Emax model for conditions where C is significantly less than EC50. This model portrays a linear trajectory of the concentration–effect relationship when drug levels are markedly below the EC50 threshold.Despite its inherent assumption of continuous effect augmentation with increasing drug...
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Pharmacodynamic Models: Logarithmic Concentration–Effect Model

The log-linear model is a pharmacological framework used to describe the relationship between drug concentration and its effect. This model is particularly relevant when the observed effects range between 20% and 80% of the drug’s maximum effect (Emax), where a near-linear relationship is observed between the log of drug concentration and the measured effect. However, the log-linear model does not predict the maximum possible effect (Emax) or the effect at zero drug concentration, limiting its...