DRUG TARGETS - AGONISTS AND ANTAGONISTS Flashcards
Define Pharmacology
The study of drugs on living systems
Define Pharmacodynamics
The mechanisms of drug action which explains variations in drug responses, adverse drug reactions and drug-drug interaction
Define Pharmacokinetics
It is the absorption, distribution, metabolism and excretion of drugs
Define agonist
A drug that binds to a receptor and produces an effect that mimics the repose to a neurotransmitter, hormone etc
What type of activity can agonist drugs have
They have both affinity and intrinsic activity (efficacY)
Define partial agonist
Cannot produce a maximum effect even though all receptors may be occupied
What is the difference between partial and full agonists
The efficacy of a partial agonist is less than that of a full agonist
Define antagonist
A drug that decreases the action of another drug or endogenous ligand
What type of activity do classic antagonist drugs have
Classic competitive antagonists have affinity for the receptor but no intrinsic activity.
In order to assert an effect what must a drug do
Bind to a specific protein on living tissues
Why can side effects occur when taking a drug
As the protein that a drug can bind to may be present in the body other than the intended site
Which proteins can drugs target in the body
- Enzymes
- Transporters
- Ion channels
- Receptors
- DNA and RNA
What are receptor operated ion channels
Those which require the binding of drugs to open their gate letting ions flow in or out of the cell across cell membranes
Name a complex receptor
G protein coupled receptor
How many domains do G protein coupled receptors
Can have 7 domains that span the cell membrane
What happens when GTP binds
Intracellularly, three subunits interact when GTP binds due to the action of other enzymes or ion channels inside the cells
How do nuclear receptors work
The ligand has to enter the cell to bind inside to its receptor
What happens when nuclear receptors are activated
The ligand-receptor complex binds to a specific DNA sequence in the nucleus
This alters the gene expression
Do G protein couples receptors respond faster or nuclear receptors
G protein couples receptors respond faster
But nuclear receptors have a longer lasting affect
Name some factors that can affect the effectiveness of a drug
- Genetics
- Age
- Diet
- Existence of disease
- Drug-drug interactions
What is the therapeutic index
The ‘window of activity’ where it can be said that the benefits outweigh the risks
What does it mean when a drug has a narrow therapeutic index
Means the toxicity or adverse drug reactions occur when the recommended maximal dose in the blood is exceeded
What does it mean when a drug has a BROAD therapeutic index
Means that the maximum blood level lays comfortably between that which is needed to induce therapeutic effect and that which would risk inducing serious toxicity
What does NNT stand for when looking at drug effectiveness
Number needed to treat
