Pharmacodynamics Flashcards
Why is Pharmacodynamics important?
Pharmacodynamics is important for drug safety, effectiveness and dosage.
What are the 2 essential functions of a receptor?
2 Essential Receptor functions: Recognition of a specific ligand molecule
Transduction of signal to a response
Define AGONISTS
AGONISTS are ligands that bind to a receptor (causing a conformational change to the active conformation) and ACTIVATE a response resulting in the DESIRED effect being produced.
Define ANTAGONISTS
ANTAGONISTS are ligands that bind to a receptor but DO NOT activate a response. No action is caused.
What are the different types of AGONISTS?
Types of AGONISTS: FULL, PARTIAL, INVERSE
How many types of AGONISTS are there?
There are 3 types of AGONISTS. FULL, PARTIAL and INVERSE
Define INTRINSIC ACTIVITY
Intrinsic Activity: the ability of a drug to produce the maximal effect. The STRENGTH of the effect, effect that can be measured, STRENGTH of the drug receptor complex
Which factors govern drug action?
Intrinsic activity and Affinity govern drug action.
Define SPECIFICITY
Specificity: selectivity for one receptor.
Depends on the binding affinity between the ligand and the binding site on the receptor
Define FULL AGONIST
Full Agonist: Agonist that has high efficacy, producing a full response while occupying a relatively low proportion of receptors.
Define Dissociation Constant KD
Dissociation Constant (KD): The amount of drug bound to a receptor at equilibrium
Define k1
k1: The rate at which a drug associates
What does PAR calculate?
PAR : Percentage of receptors that have drugs bound to them. Occupancy. It can be calculated NOT measured.
Define AFFINITY
AFFINITY: ability of a ligand to bind to a receptor. How tightly a ligand binds to a receptor.
Define EFFICACY
EFFICACY: Ability to initiate events that lead to a response
Define POTENCY
POTENCY: Relative amount of drug to produce an effect. Combination of AFFINITY and INTRINSIC ACTIVITY
Define PARTIAL AGONIST
Partial Agonist: Agonist that is unable to produce maximal effect despite occupation of all receptors. Lower efficacy than full agonist.
Define INVERSE Agonist
Inverse Agonist: Agonist that keeps receptors in inactive form. Eliminates normal “basal” activity.
What does a small kD indicate?
A small kD indicates a high affinity between the drug and receptor
Do all drugs work by binding to receptors?
No, not all drugs work by binding to receptors.
Name 3 types of drugs that work without binding to a receptor
Antacids, Fluid Expanders and Anaesthetics work without binding to receptors
Describe the adenosine antagonists and give an example of one
*Caffeine is an adenosine antagonist- similar structure to adenosine
*Adenosine antagonists facilitate dopamine release
What are units of equilibrium dissociation written as?
Units of equilibrium dissociation: 1x10-8M or 10nm
There is an ___________ relationship between the kD and the affinity
There is an inverse relationship between the kD and the affinity
What is a G protein coupled receptor?
Integral membrane protein that contain seven transmembrane (TM) α-helices.
Largest and most diverse group of membrane receptors in eukaryotes.
Most receptors are ___________.
Most receptors are PROTEINS.
All receptors are _____________.
Receptors are MACROMOLECULES.
Where are receptors usually found?
Receptors are usually found on the:
* Cell surface
*Cytoplasm
*Nucleus
Receptors are ________ specific
Receptors are LIGAND specific
How many types of receptors are there?
There are 5 types of receptors:
* Internal (intracellular receptors)
*Transmembrane (cell-surface) receptors
*Ion-channel linked receptors
*G-protein linked receptors
*Enzyme-linked receptors
Intracellular (internal) receptors
Intracellular receptors:
*Found in the cytoplasm
*Respond to hydrophobic molecules
*Usually involved in gene expression
Transmembrane (cell-surface) receptor
Transmembrane (cell-surface) receptors:
*Bind to external ligands
*Performs signal transduction
*Three main types: Ion-channel linked, G-protein linked, enzyme-linked
