KINETICS - M1.2 (Definitions)

Calculus

An important mathematic tool for analyzing drug movement quantitatively since drugs are considered in a dynamic state

Differential equation

Used to relate the concentrations of drugs in various body organs over time

Integrated equation

Frequently used to model the cumulative therapeutic or toxic responses of drugs in the body

differential calculus

Branch of calculus that involves finding the rate at which a variable quantity is changing

Noyes-Whitney Equation

The rate at which the drug dissolves is determined by the rate of drug diffusing away from the surface of the solid drug. It is expressed by a differential equation called the _____________

Concentration = dependent; Time = independent

Among Concentration of drug in the body and Time, which of the two is the dependent variable and the independent variable?

Integration

It is the reverse of differentiation; Considered a summation definite integral

definite integral

A ____________________ of a mathematical function is the sum of individual areas under the graph of that function

Trapezoidal rule

A numerical method frequently used in pharmacokinetics to calculate the area under the plasma drug concentrationversus-time curve, called area under the curve (AUC)

Graphing

The construction of a curve or straight line by plotting observed or experimental data on a graph

Graphing

Important method of visualizing relationships between variables

Abscissa

Other name for x axis

Ordinate

Other name for y axis

Straight line

Very useful for accurately predicting values for which there are no experimental observations

Horizontal

As the value of m approaches 0, the line becomes more ___________

Vertical

As the value of m becomes larger, it becomes more _________

Rate of a reaction

The rate of a chemical reaction of a process is the velocity with which the reaction occurs

rate of a reaction

The ______________ is determined experimentally by measuring the disappearance of a drug at given time intervals

order of reaction

The ______________ refers to the way in which the concentration drug or reactants influences the rate of a chemical reaction or process

Zero-order reaction

The order of reaction wherein the drug concentration changes with respect to time at a constant rate

Zero-order reaction

Order of reaction that is mostly occurring when the elimination system is saturated

Rate Constants

It characterizes the change of drug concentration in a particular reference region

Ethanol, aspirin, phenytoin

Examples of drugs that display zero-order elimination (3)

First-order reaction

The drug concentration changes with respect to time equal the product of the rate constant and the concentration of drug remaining

First-order reaction

The order of reaction wherein the rate of elimination is proportional to the drug concentration

First-order reaction

The order of reaction wherein the elimination processes are not saturated and can adapt to the needs of the body, to reduce accumulation of the drug

First-order reaction

95% of the drugs in use at therapeutic concentrations are eliminated by this order of reaction

Zero order

In this order of reaction, the rate is constant with respect to time

Zero order

In this order of reaction, the rate constant with respect to time changes as the concentration changes

First order

In this order of reaction, the rate will change with respect to time as concentration changes

First order

In this order of reaction, the rate constant remains constant with respect to time

half-life (T½)

Expresses the period of time required for the concentration of a drug to decrease by one half

half-life (T½)

Is the time required to decrease the initial dose of drug by 50% (one half of original value)

half-life (T½)

It determines the dosing interval necessary to obtain the desired Cp of the drug

half-life (T½)

It predicts how long it will take a drug to reach steady-state levels

half-life (T½)

It predicts the accumulation of a drug in the body for a specific dosing interval

half-life (T½)

It predicts how long it will take a drug concentration to decrease to a lower concentration

96%

All drugs are decreased by __________ after 4 half-lives

4-5 half-lives

During multiple dosing or continuous IV infusion it takes approximately __________ half-lives to reach steady-state levels

First order reaction

In this order of reaction, no matter what the initial amount or concentration of the drug is, the time required for the amount to decrease by one half is constant

Zero order reaction

The half-life of this order of reaction is proportional to the initial amount or concentration of the drug and is inversely proportional to its rate constant