Week 2 Pharmacodynamics Flashcards
pharmacodynamics
The study of the biochemical and physiologic effects of drugs and the molecular mechanisms by which those effects are produced
pharmacodynamics
The study of what drugs do to the body and how they do it
Dose-Response Relationships
Relationship between the size of an administered dose and the intensity of the response produced
3 phases occur
maximal efficacy
the largest effect that a durg can produce
relative potency
The amount of drug that must be given to elicit an effect
Rarely an important characteristic of the drug
Can be important if a lack of potency forces inconveniently large doses
Implies nothing about maximal efficacy; refers to dosage needed to produce effects
receptor
any functional macromolecule in a cell to which a drug binds to produce its effects (generally proteins)
Technically, receptors can include enzymes, ribosomes, and tubulin
The term receptor is generally reserved to refer to the body’s own receptors for hormones, neurotransmitters, and other regulatory molecules
receptor binding
The binding of a drug to its receptor is usually reversible
Receptor activity is regulated by endogenous compounds
When a drug binds to a receptor, it will mimic or block the action of the endogenous regulatory molecules and increase or decrease the rate of physiologic activity normally controlled by that receptor
drugs cannot
give cells new functions
the more selective a drug is
the less side effects it will produce
what makes selectivity possible
receptors
each type of receptor participates in the regulation of just a few processes
body has receptors for each of the following
Neurotransmitters
Hormones
All other molecules in the body used to regulate physiologic processes
simple occupancy theory
cannot explain different maximal efficacies of drugs
affinity
strength of the attraction between drug and receptor
intrinsic activity
ability of the drug to activate a receptor upon binding
agonists
molecules that activate receptors
endogenous regulators
agonists
what has high affinity and intrinsic activity
agonists
antagonists
produce their effects by preventing receptor activation by endogenous regulatory molecules and drugs
what has affinity but no intrinsic activity
antagonists
if there is no agonist present
antagonist will have no observable effect
noncompetitive antagonists
Bind irreversibly to receptors
Reduce the maximal response that an agonist can elicit (fewer available receptors)
Impact not permanent (cells are constantly breaking down “old” receptors and synthesizing new ones)
Example: Omeprazole
competitive agonists
Compete with agonists for receptor binding
Bind reversibly to receptors
Equal affinity: Receptor occupied by whichever agent is present in the highest concentration
partial agonists
Compete with agonists for receptor binding
Bind reversibly to receptors
Equal affinity: Receptor occupied by whichever agent is present in the highest concentration
drug responses that do not involve receptors
Simple physical or chemical interactions with other small molecules
Examples of receptorless drugs:
Antacids, antiseptics, saline laxatives, and chelating agents
