Pharmacodynamics And Pharmacokinetics Flashcards
What are pharmacodynamics?
How a drug affects the body (time course and intensity of effect)
What are pharmacokinetics?
How the body affects the drug (absorption, distribution, metabolism, and excretion)
What are the characteristics of pharmacodynamics?
Potency
Efficacy
Therapeutic effect
Side effects
Receptors
What does a more potent drug equal?
Less drug required for a specific response
What is efficacy?
Drugs ability to produce a desired response
What is effectiveness?
How useful the drug is
Enteral drugs
Oral and easiest to self administer
What are enteral drugs absorbed by?
Small intestine
What must an enteral drug have?
High lipid solubility
What is the first pass effect of an enteral drug?
Metabolism/destruction of drug molecule in liver before reaching its site of action
What are paraenteral drugs?
Bypass the GI system and have a more direct route to target site
What are paraenteral drugs not subject to?
First pass effect
Bioavailability
% of drug administered that reaches the bloodstream
What does bioavailability depend on?
Route of administration, drugs ability to cross membranes, and extent of first pass metabolism
What are the advantages of taking drugs orally?
Easy, safe, and convenient
What are the advantages of taking drugs sublingual?
Rapid onset, not subject to first pass metabolism
What is the advantage of taking drugs rectally?
Local effect on rectal tissues
What is the advantage of taking drugs through inhalation?
Rapid onset, direct effect for respiratory disorders (large surface area)
What is the advantage of taking drugs through an injection?
More direct administration to target tissues
What is the advantage of taking drugs topically?
Local effects on surface of skin
What is the advantage of taking drugs transdermally?
Puts drugs into body without breaking skin and can provide steady prolonged delivery
What is the importance of tissue permeability in drug administration?
Highly lipid soluble molecules cross membranes more easily
Where will bloodstreams carry drugs to?
Highly perfused organs
What is sub cellular protein binding?
Drug gets trapped within the cell (anti-depressants)
Where does negative venule pressure pull drug?
From tissues back into blood
Where does positive arteriole pressure draw drugs to?
Blood into tissue spaces
What happens to drug that is bound to plasma protein?
Cannot leave the blood to distribute into tissues and is inactive
What happens to a drug that is unbound from plasma protein?
Distribute from blood to tissues and is active
What is the volume of distribution?
Amount of drug administered/ concentration of drug in plasma
What happens if the volume of distribution is greater than the total amount of body water?
Drug is being concentrated in tissues
What happens if the volume of distribution is less than the total amount of body water?
Drug is being retained in the bloodstream
What is clearance?
One organ or all organs ability to clear a drug
What are the factors that influence clearance?
Blood flow to organ
Extraction ratio
Concentration
What is extraction ratio?
Fraction of drug removed from the plasma as it passes through the organ
What is half life a function of?
Both clearance and volume of distribution
What is an agonist?
Drug capable of binding to a receptor and activating change in a cells function
What is an antagonist?
Drug that binds to a receptor and blocks activity
Where are drugs metabolized?
At the liver and lungs via biotransformation
What are properties that affect a drugs elimination rate?
Clearance and half time
