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Drug Foundations


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How do drugs interact with biological targets (___) to produce a change in the organism?
(receptors)/ Drug + Receptor --> Drug-Receptor Interaction (binding) --> signal
What is a drug?
molecules that interact w/ specific molecular components of an organisms
trying to manipulate endogenous targets
What is a receptor?
A drug Target. macromolecules that upon binding to a drug, mediate biochemical and physiological change w/in the organism.
How do side-effects work?
when there is an unwanted drug-target
Four Major types of drug targets (receptors) are?
1) Transmembrane ion channels
2) Transmembrane receptors coupleld to intracellular G proteins
3) Transmembrane receptors w/ ezymatic cytosolic domains
4) Intracellular receptors (cytoplasmic or nuclear)
Transmembrane ion channels
bind, causing alteration in the channel's conductance
transmembrane receptors coupled to intracellular G-proteins
coupled to G protein (ntracellular)/ drug binds to extracellular surface
transmembe receptors w/ enzymatic cytosolic domains
Drug binds to exptracellular and cause a change in signaling within the cell by activating or inhibiting an enzymatic intracellular domain of same receptor molecule.
Intracellular receptors (cytoplasmic or nuclear)
drugs diffuse through plasma membrane and bind to cytoplasmic or nuclear receptors (pathway used by lipophilic drugs, drugs that bind to steroid hormone receptors)
receptor structure
1) AA have large hydrophobic domans are able to reside in plasma membrane because of the membrane's high lipid content
2) other drug receptors, including a number of transcrition factors, have only hdrophilic domains and can reside in they cytoplasm, nucleus, or both.
Drug Structure
1) structure of a drug effects its ability to gain access to the receptors
2) drugs that are highly soluble to water are less able to pass through the plasma membrane and bind to target molecules in the cytoplasmic receptors
3) drugs that are highly lipophilic, such as steroid hormones are able to pass through the hydrophobic lipid environment of the plasma membrane without channels or transporters
molecules that bind and activate a target
molecules that inhibit the ability of their targets to be activated by physiolgoical or pharmacolgic agonist
competitive antagonist
drugs that directly block the binding of a physiological agonist
noncompetitive/ uncompetitive antagonist
ddrugs that bind to other sites on the target molecule, and thereby prevent the conformational change required for receptor activation.
G-protein found in membranes, 7 TM has external __, internal ___.
external N terminal, internal C terminal.
What neurotransmitters use GPCRs and ligand-gated ion channels?
GABA, glutamate, serotonin, and acetylcholine.
Three Types of Transmembrae Channel are:
1. Voltage-gated
2. Ligand-gated
3. Second messenger regulated
Voltage-gated channels:
Change in transmembrane voltage gradient- alters ion conductance.
Ligand binds to ion channel- alters ion conductance.
Ion Channels include 2 types:
Ligand-gated and Voltage-gated
Second messenger regulated ion channels:
binding of a ligand to a G-protein coupled receptor-generates a second messenger that regulates ion conductance of a channel
Relative speeds of receptors in descending order:
1. Ion channels mediate FAST signalling events (speeds of around one millisecond)
2. G protein-coupled receptors (GPCR) use mechanism that are at least one hundred times slower
3. Transemembrane receptors with cytosolic domains (100s milliseconds)
4. steroid/hormone receptor family of nuclear receptors (respond in minutes to hour)
Cellular excitability
ability of a cell to generate and propogate electrical potentials.
Excitable tissues:
neurons and muscle cells utilize action potentials to propagate electrical signals across the plasma
Chemical and electrical signaling via _____ involves a flow of ions across plasma or endo-membranes
ion channels
movement of ions cross a membrane tends to: (3)
1) change intracellular concentrations of ions- may be critical for a biological event "second messengers"
2)Change the electrical potential of the membrane
3)Regulate voltage-dependent ion channels
Neurons and cardiac mayocytes have a resting potential of:
-60 - 80 mV
positive and negative charge is ___ on both sides of the plasma membrane
____ is differentially permeable to different ions

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