Midterm 1 Flashcards
What is the EC50? How do you find it on a graph?
The dose that is effective in 50% of the time, assuming everyone is the same. Found at Y=50
Think: effective
What is the KD50?
The dose that proves lethal 50% of the time
Think: kill dose
What is the ED50?
Similar to the EC50, but considering variability
Think: effective dose
What is the LD50?
Similar to KD50, but considering variability
Think: lethal dose
What is the therapeutic index? How is it calulated?
The ratio of dose required for a desirable effect to undesirable effect
TI=LD50/ED50
TI=KD50/EC50
What is potency? How can you gauge it on a graph?
The extent of the drug’s effects
More potent = leftmost on graph
What is drug efficacy? How can you gauge it on a graph?
A drug’s ability to produce a maximum, biologically functional response
Higher curve = more effective
What are primary effects? Secondary effects?
Primary: the intended reason for taking the drug
Secondary: side effects, anything else
Give an example of a polar ion
Therosine
Name some charged ions
Arginine+, Histidine+
Name some hydrophobic ions
Valine, Isoleucine, Leucine, Methionine, Tryptophan, phenylalanine
Name some special case ions
Cystine, glycine, proline
What type of bond is the strongest? Weakest?
Strong: Covalent bond
Weak: Hydrophobic bond
Explain lipid diffusion
The migration of lipophilic and non-charged ions through the cell membrane. Guided by concentration gradients
Explain aqueous diffusion
Pores allow the passage of specific sized molecules through tight junctions
NOT through blood-brain barrier
Explain the relation between pH and PKA
PKA is the pH at which 50% of ions are charged
Charged drugs cannot pass barrier
How can you predict the charge of an ion from pH and PKA?
PKA>pH = weak base is neutral
PKA<pH = weak base is ionic (charged)
What is PKA?
The pH at which 50% of the molecules are charged
Explain active transport
Specific molecules bind to specific carriers to be transported over the barrier
What is saturated active transport? Inhibited?
Transport that requires no energy
Blocked transport
Explain endo/exocytosis
Passing over (in or out) the membrane, surrounds the molecule in a vesicle
What is ADME?
Absorption, Distribution, Metabolism, Excretion
What is bioavailability?
how much of the drug ‘makes it in’ or takes effect on the body
What are the different routes of administration?
Parenteral: Injection, Inhalation, Transdermal, Nasal, Topical
Enteral: Oral, rectal
What are the types of injections? (6)
Sub-q: under skin
Intramuscular: muscle
Intraperitoneal: peritoneal cavity
Intravenous: vein
Intrathecal: between skull and V1
Intracerebroventricular: brain ventricles
How do injections get absorbed into the body?
Injection makes its way into bloodstream
Makes its way in deoxygenated blood through heart to lungs
Oxygenated and sent back through heart to body to brain
How are inhaled substances ADME?
Substance inhaled into lungs(A)
Gas exchange allows drug to pass into oxygenated blood, pumped through heart to brain and body (D)
Slow metabolism throughout body (M)
Expelled by breathing out (E)
THC ADME when inhaled
Inhaled particles remain in lung and absorb into bloodstream for distribution (A,D)
Body metabolizes and expels like solids (M,E)
How are oral substances ADM?
Absorption through the walls of the stomach and intestine (A)
Into bloodstream via villus, pass throughout body (D)
Breakdown in saliva, stomach acid, liver, kidneys (M)
What is first pass metabolism?
Any drug absorbed via the digestive system is pre-metabolized in the stomach, gut, and liver
How are transdermal substances absorbed?
Lipophilic substances seep in through S.C (top layer of skin)
What are distribution compartments?
How do they affect distribution
Fat, bone, intracellular fluid, extracellular fluid
Fat and bone have reservoirs that hold on to substances (slower release)
Where does most of metabolism occur?
Liver and Kidneys
Explain phase 1 metabolism
Give examples of the enzymes
Enzymes break down the molecule to make them polar
CYP1, CYP2, CYP3, CYP3A4
Explain phase 2 metabolism
Drugs are transformed into conjugates
How do the kidneys aid in metabolism?
Filers certain substances out of blood, sends waste to be eliminated
What are first-order kinetics?
The elimination rate of substances dependent on concentration
What is half-life when discussing elminination?
Half life is the time it takes for the body to eliminate 50% of the substance
What is zero-order kinetics?
When a substance is eliminated at a constant rate, independent of concentration
What is the therapeutic window?
the range of a substance’s concentration in the blood between maximum and minimum efficacy
How can you determine the therapeutic window?
The same as the therapeutic index
KD50/EC50
LD50/ED50
What factors affect PK/PD?
Genetics, age, sex, state of subject, diet
Explain how the state of a subject affects PK/PD
Alcoholics create more of the enzyme (alcohol dehydrogenase) for breakdown, thus it is faster
Explain how age can affect PK/PD
Children and fetuses do not produce alcohol dehydrogenase enzyme, cannot break down
What is an agonist effect?
How does it relate to drugs?
A molecule that activates the receptor it binds to
An drug that produces an agonist effect will activate the receptor, but does not stop when overstimulated
What is an antagonist effect?
How does it relate to drugs?
A molecule that blocks the receptor it binds to
A drug that is an antagonist will block a ligand from activating the receptor
What is a full agonist effect?
The maximum activation response to molecule binding
What is a partial agonist effect?
Activates to mid potential, above average but not full
What is a competitive antagonist?
When a molecule will compete for the receptor
What is an irreversible antagonist?
A molecule that kicks everything else off the receptor to block it
What is an inverse agonist effect?
How does this relate to drugs?
When a GPCR spontaneously activates due to an absence of ligands
A drug that takes this effect will reverse that spontaneous activation
What is an allosteric modulator?
A substance that binds to additional receptors, altering the effect of primary binding
What is PAM? What does it mean
Positive allosteric modulator
A substance that enhances the primary effect
What is NAM? What does it mean
Negative allosteric modulator
A substance that inhibits/reduces the primary effect
What is a 1+1=0 drug interaction? Give an example
An antagonist effect, drug B cancels/reduces drug A
Naloxone for opiods
What is a 1+1=2 drug interaction?
An additive effect, drug B adds to the effect of drug A
What is a 1+1=3 drug interaction?
A superadditive / synergism effect, the combined effect of A with B are greater than the effect of A and B (A+B) > (a) + (b)
What is a 0+1=2 drug interaction?
A potentiation effect, drug A has no effect unless taken with drug B
How is resting potential maintained?
Simple diffusion, electrostatic charge, differential permeability, transporter pumps
How does simple diffusion maintain resting potential?
Na+, K+, Cl-, A- move along their concentration gradient, in and out of the cell to maintain an inner difference of -70mV
How does electrostatic charge maintain resting potential?
K+, Na+ are repelled by the more positive charge outside the cell, inclined to stay internal
Cl-, A- are repelled by the more negative charge inside the cell, inclined to stay external
How does differential potentiation maintain resting potential?
Non-gated ion channels are open to allow K+ and Na+ to pass as needed
How do transporter pumps maintain resting potential?
Active exchange of K+ (in) for Na+ (out)
Sodium-potassium pump
How is an action potential generated (7 steps)
- Threshold met
- Na+ enter
- K+ leaves
- Na+ channels close
- K+ keeps leaving (repolar - hyperpolarization)
- K+ channels close causing (cell is hyperpolar)
- Excess external K+ diffuses away
What is an EPSP? Explain it
Excitatory Post Synaptic Potential
Causes an excitation response, starts a process
What is an IPSP? Explain it
Inhibitory Post Synaptic Potential
Causes an inhibition response, stops something
How does an ionotropic receptor work?
Charged ions (Na+, K+, Cl-) bind to the receptor to activate or inhibit
What are the products of ionotropic receptors?
IPSP or EPSP
How does a metabotropic receptor work?
G-protein coupled molecules bind to the receptor and initiate a second messenger
What are the second messengers associated with metabotropic receptors?
cAMP
cGMP
What does the second messenger cAMP do?
cGMP?
Activates PKA
Activates PKG
Proteins (enzymes) that alter the functioning of other receptors
What is Glutamate?
How is it synthesized? Reuptake/Breakdown?
Role?
Excitatory amino acid
Synthesized from glutamine
Reuptake via EAAT
Role: cell plasticity, learning + memory
What is the AMPA?
How does it work?
Glutamate receptor
Ionotropic
Glutamate/drug binds
Na+ IN, K+ OUT
Local depolarization and at Mg2 site
EPSP
What is NMDA?
How does it work?
Glutamate receptor
Binding
Depolarizing opens Mg2 site
Glutamate and glycine receptors bind
Na+, Ca2+ INTO cell
What receptor does PCP affect? How?
NMDA
Antagonist effect
What is GABA?
How is it synthesized? Reuptake/Breakdown?
Role?
Inhibitory amino acid
Synthesized by GAD from glutamate
Reuptake by GAT
Role: memory, impulse, decision making
What is GABA(A)?
How does it work?
GABA receptor
Ionotropic
Substance binds, Cl- passes into cell
IPSP
What receptor does Alcohol affect?
How?
GABA(A)
Binds to receptor, opening flow of Cl- into cell
Inhibits actions
Affects: memory formation, decision making, impulse control
What is Dopamine?
How is it synthesized? Reuptake/Breakdown?
Role?
Monoamine
Synthesized from Tyrosine
Reuptake by DAT
Breakdown by MAO, COMT
Role: reward-related processes, motor behaviour
What is the D1?
How does it work
Dopamine receptor
Metabotropic
Binding activates the G protein
Stimulate cAMP (second messenger) production
Increase excitability
What is the D2?
How does it work?
Dopamine receptor
Metabotropic
Binding activates the G protein
Inhibit cAMP (second messenger) production
Decrease excitability
What effect does Cocaine have?
How?
Agonist effect on dopamine
Blocks DAT reuptake, causing dopamine to keep binding and overstimulate cell
What effect do methamphetamines have?
How?
Agonist effect on dopamine
Reuptake reversal
Mimics dopamine and binds to D receptors
Excess dopamine binds after
Overstimulate cell
Affects: euphoria in reward path