PHARMACODYNAMICS 4 Flashcards
Physiologic antagonist occurs when drugs act independently at different receptors. Examples of this are:
Histamine + Epinephrine
Histamine + Salbutamol
Glucocorticoid + Insulin
Also known as true antagonist because no receptor is involved
Chemical antagonist
Examples of Chemical agonist
Paracetamol + N-Acetylcysteine
Warfarin + Vitamin K
(T/F) Competitive antagonism is irreversible, and Non-Competitive antagonism is reversable
False (Competitive ago = reversable)
(T/F) Competitive antagonist competes in same site, non-competitive binds to allosteric binding site.
True
Examples drugs for non-compe antagonism
Phenoxybenzamine
DNA alkylating agent
Refers to the regulation of an enzyme or other protein by binding an effector molecule at proteins allosteric site
Allosteric Modulation
Type of allosteric modulation that occurs when binding one ligand enhances the attraction between substrate. AKA Allosteric activation
Positive allosteric modulation (ex. Hemoglobin + oxygen) 4 oxygen each
Type of allosteric modulation that occurs when binding decreases the affinity for substrates. AKA allosteric inhibition
Negative Allosteric Modulation
Example of Negative Allosteric Modulation
Strychnine block Glycine receptors
Caused by continuous prolonged exposure of receptors to drugs leading to desensitization
Down regulation
Caused by prolonged/continuous use of receptor blockers that causes denervation
Sensitization / Up-regualtion
Caused by long term exposure then sudden cessation of drug use that causes upregulation
Hyperactivity/Supersensitivity
Theory by langley from 1905 known as “Fit into a receptor”
Lock and Key theory
Theory that states that it alters the conformation of its binding site / causes change in the shape.
Induced fit theory
Theory that states that drug effect is directly proportional to the number of receptors occupied. it describes the behavior of agonist and antagonist “greater no. greater effect”
Occupancy theory
Maximal drug is response is not equal to the maximal tissue response. (existence of partial agonist drugs)
Ariens theory 1954
Theory added the concept of stimulus and efficacy
Stephenson’s theory 1956
theory that describes relationship between dose and response “behaviour of full agonist”
Clark’s theory 1934
Also known as paton theory “collision between drug and receptor”
Rate Theory
