Pharmacokinetic Models | One Compartment Open Model IV Bolus | Unit 3 Biopharmaceutics 6th Sem
This lecture covers pharmacokinetic models in biopharmaceutics, focusing primarily on the one compartment open model for IV bolus injection. The instructor explains compartment models, their types, and how to calculate key pharmacokinetic parameters like elimination rate constant and half-life.
Summary
This educational video is part of Unit 3 in 6th semester Biopharmaceutics, focusing on pharmacokinetic models. The instructor begins by explaining that pharmacokinetic models are hypothetical tools used to understand drug ADME (Absorption, Distribution, Metabolism, Excretion) in the body. He introduces three main approaches: compartment models, non-compartment models, and physiological models, with primary focus on compartment models. The lecture extensively covers mamillary models where the blood acts as a central compartment connected to peripheral compartments representing body tissues. The instructor explains the notation system for rate constants (K) between compartments and demonstrates how drug movement is represented using arrows and mathematical expressions. The main focus shifts to the one compartment open model for IV bolus injection, which is identified as the most important exam topic. In this model, the entire body is considered as a single uniform compartment with instantaneous drug distribution. The mathematical derivation shows how to calculate elimination rate constant (ke), elimination half-life (t1/2 = 0.693/ke), and clearance from plasma concentration versus time data. The instructor emphasizes that this is the most frequently asked long-answer question in exams and provides the mathematical framework including differential equations and their integration to derive the final logarithmic relationship used for parameter calculation.
Key Insights
- The instructor identifies that from the entire Unit 3, only one question consistently appears in exams - calculating elimination rate constant and half-life using one compartment open model for IV bolus
- Pharmacokinetic models are hypothetical models that don't actually exist but are assumed to help calculate pharmacokinetic parameters and understand drug ADME processes
- In mamillary models, blood serves as the central compartment and all other body tissues act as peripheral compartments that connect directly to blood, with elimination always occurring from the central compartment only
- For IV injection models, the absorption arrow (K01) is never drawn because the entire drug dose enters the body compartment instantaneously, unlike oral models where gradual absorption occurs
- The one compartment model assumes the entire body behaves as a single compartment with instantaneous and uniform drug distribution, no barriers, and constant elimination rate following first-order kinetics
Topics
Full transcript available for MurmurCast members
Sign Up to Access