PHARMOCOKINETICS AND Dynamics Flashcards
how the drug affects the body
Pharmacodynamics
how the body acts on the drug
Pharmacokinetics
the study of the interactions
between the chemical
components of living systems
and the foreign chemicals,
including drugs that enter those
systems.
Pharmacodynamics
Drugs usually work in one of four ways:
To replace or act as substitutes for
To replace or act as substitutes for
missing chemicals
To increase or stimulate certain
cellular activities
To depress or slow cellular
activities
To interfere with functioning of foreign
cell
Specific areas on cell
membrane
Receptor Sites
They react with certain
chemicals to cause an effect
within the cell
Receptor Site
break down the
reacting chemicals and open
the receptor site for further
stimulation
Enzyme
Interact directly with receptor sites to cause the same
activity that natural chemicals would cause at that
site
Agonist
Prevent breakdown of natural chemicals that are stimulating the receptor site
Inhibitor
React with receptor sites to block normal stimulation, producing no effect
Competitive Antagonist
React with specific receptor sites on a cell and by reacting there prevent the reaction of another chemical with a different receptor site on that cell
Non competitive Antagonist
Molecules of drug A react with specific
receptor sites on cells of effector organs
and change the cells’ activity.
Antagonist Interaction with receptor sites on a cell
Drug A and drug C have an affinity for
the same receptor sites and compete
for these sites; drug C has a greater
affinity, occupies more of the sites, and
antagonizes drug A.
Competitive antagonism
Drug D reacts with a receptor site that is
different from the receptor site for drug
A but still somehow prevents drug A
from binding with its receptor sites.
Noncompetitive antagonism
Drugs also can cause their effects by interfering with the enzyme systems that act as catalysts for various chemical
reactions.
Drug enzyme interaction
Drugs also can cause their effects by interfering with the enzyme systems that act as catalysts for various chemical
reactions.
Drug enzyme interaction
work in a cascade fashion, with one
enzyme activating another, and then that enzyme activating another, until a cellular reaction eventually occurs.
Enzyme system
The ability of a drug to attack only those
systems found in foreign cells
Selective Toxicity
pharmacokinetic considerations
- Onset of drug action
- Drug half life
- Timing of peak effect
- Duration of drug effect
- Metabolism of drug
- Site of excretion
involves the study of absorption, distribution, metabolism
(biotransformation), and excretion of drugs
Pharmacokinetics
The amount of drug that is needed to cause a therapeutic effect
Critical Concentration
A higher dose than that usually used for treatment to reach critical concentration quickly
Loading Dose
Dynamic Equilibrium Processes
• Absorption from the site of entry
• Distribution to the active site
• Biotransformation (metabolism) in the liver
• Excretion from the body
Refers to what happens to a drug from the time it is introduced to the body until it reaches the circulating fluids and tissues
Absorption
