Pharmacodynamics Flashcards
Adverse effects
unintended
What is the study of adverse effects called
pharmacovigilance
What are physical interactions on targets for drug action
osmotic diuretics
antacids
radioactive iodine
Osmotic diuretics
molecules move through the body dragging water via osmosis until secreted
Antacids
directly interact with acid in GI, physiologic antagonism
Radioactive Iodine
actively concentrated in thyroid and radiation will destroy tissue 2-3 mm causing focal controlled destruction
Ionotropic receptors
proteins in cell membrane that make a pore/tunnel. Usually ligand gated, something binds to them causing a change in shape allowing a large influx in ions (think neurotransmission).
Drugs can activate of prevent opening.
Metabotropic Receptors
G-protein/7TM
Transduce extracellular signal to intracellular by activating G protein messenger system
Drug binds to receptor outside the cell caause G proteins inside the cell to bind to the receptor and take up GTP which gives them enough energy to move to a target enzyme or channel to cause an action
(Common in smooth muscle functions)
Side effects
secondary to intended effect, can be good or bad
Kinase-coupled receptors
Transmembrane proteins with and extracellular and intracellular portion that has enzymatic activity.
Phosphorylation and activation of proteins which activate effectors.
Insulin receptors are this type
Nuclear Receptors (Transcription Factor Receptors)
Located in the cytoplasm but after ligand binds translocate to nucleus and bind to a response element within DNA to initiate specific gene transcription.
Ex- steroid and thyroid hormones
Up regulation
increase in # of receptors and increase of effect of drug
Down regulation
reduction of effect
May be part of normal cell metabolism or tolerance or tachyphylaxis
How can drugs affect Voltage gated ion channels?
physical obstruction
modulate opening or closing of channel
How can drugs affect enzymes?
Can be analogs
Prodrugs
False substrates leading to formation of abnormal metabolites
How can drugs alter carrier proteins?
Preventing uptake
Preventing output
Ligand
anything that binds to a recognition site
Agonist
mimics the effect of endogenous ligand
Full agonist
binds to receptor for maximal response
Partial agonist
not as much effect as full agaonist but prevents anything else from binding
Reverse agonist
binds to the receptor and causes opposite effect
Antagonist
Binds to receptor and does nothing but block the receptor
Competitive antagonism
binds and releases as long as its present. If agonist is present they will compete, who binds more often is determined by concentration and affinity. Can be reversible or irreversible.
Efficacy
the maximal effect a drug can have (e=1 is full effect)
Potency
Comparison of the concentration of two drugs needed to induce the same magnitude effect
EC50
Effective Concentration 50%, concentration at which the drug produces 50% of its maximal effect. Applies only in vitro.
ED50
Dose that produces a result in 50% of the animals. In vitro.
Therapeutic Index
LD50/ED50
Do you want a high or low therapeutic index?
High, low indicates a more dangerous drug.
Onset of action
The time required after drug administration for a response to be observed
Duration of action
length of time that a drug is effective
