Multi Exponential Pharmacokinetics Flashcards

Vocabulary flashcards for multi exponential pharmacokinetics lecture.

Multi Exponential Pharmacokinetics

An advanced pharmacokinetic model used to describe drugs that do not distribute instantaneously throughout the body, often involving multiple compartments.

Mono Exponential Pharmacokinetics

A simpler pharmacokinetic model assuming instantaneous drug distribution and elimination from a single compartment.

Two Compartment Model

A multi exponential model dividing the body into a central compartment (blood, plasma, highly perfused tissues) and a peripheral compartment (poorly perfused tissues).

Central Compartment

In a two compartment model, it includes blood, plasma, and highly perfused tissues like the liver and kidneys.

Peripheral Compartment

In a two compartment model, it includes poorly perfused tissues like bone and fat.

Rate Constants

Govern the dynamic equilibrium between the central and peripheral compartments in a two compartment model, dictating drug distribution and redistribution.

Compartmentalization

The tendency of some drugs (e.g., lipophilic or hydrophobic drugs) to localize in specific tissues or compartments.

Biphasic Behavior

Observed in two compartment models, with an initial distribution phase followed by an elimination phase on a concentration over time plot.

Distribution Phase (Alpha Phase)

The initial, rapid decline in drug concentration due to both distribution to the peripheral compartment and elimination from the central compartment.

Elimination Phase (Beta Phase)

The slower, terminal decline in drug concentration primarily dominated by drug elimination from the central compartment.

First Order Kinetics

The assumption that drug elimination is proportional to drug concentration.

Homogeneity

The assumption that drug is evenly distributed within each compartment.

Method of Residuals (Feathering/Stripping)

A technique used to separate the distribution and elimination phases from a biphasic curve to determine individual rate constants.

Volume of Distribution (Central Compartment)

The volume in the blood compartment immediately after drug administration.

Volume of Distribution (Steady State)

A proportionality constant relating the plasma concentration and the amount of drug remaining in the body at a time following steady state (five to seven half-lives).

Half-Life (Alpha Phase)

The time taken for the concentration of drug to decrease by 50% during the distribution phase (0.693/alpha).

Half-Life (Beta Phase)

The time taken for the concentration of drug to decrease by 50% during the elimination phase (0.693/beta); represents the true biological half-life.

Biological Half-Life

The terminal half-life that factors in both redistribution and elimination, providing a more accurate measure of how long a drug resides in the body.

K12 and K21

Intercompartmental transfer rate constants; K12 is the distribution rate constant from the central to the peripheral compartment, and K21 is the redistribution rate constant from the peripheral to the central compartment.

KEL (or K10)

The elimination rate constant from the central compartment.

AUC (Area Under the Curve)

A measure of drug exposure, calculated from zero to infinity.