Pharmacology Flashcards
Therapeutic index
TI= LD_50/ED_50
- LD50 = The dose required to kill half the tested population.
- ED50 = The dose of a medication that produces the desired pharmaceutical effect in 50% of the tested population.
TRUE OR FALSE
The lower the therapeutic index is the safer the drug is
FALSE
Infact, the higher the TI is the safer the medication will be.
How to plot a log concentration response curve
- IF conc. is in nM, convert to M.
- Log Molar concentrations.
- Plot the scale on the Y-axis (response[mm]).
- Plot the scale on the X-axis (Log[Conc]).
- Plot line of best fit (sigmoidal line)
- Find the half of the Y-axis maxinum and trace down its correlated X-axis value on the graph.
- Reverse log this value.
- EC50 should be in M
How to determine the EC50 on a log concentration graph
- Half the Vmax.
- Trace the correlated X-axis value from the line.
- Reverse log this value -> value should be in M
How to plot a Saturation binding curve
- Plot the concentration on the X-axis
- Plot the binding (cpm) on the Y-axis
- Plot the data points on the graph
- Draw a line of best fit
- Determine Bmax
- Determine kd
How to determine the kd in a saturation binding curve
- Determine Bmax Y-value
- Half the value
- Trace the Y-value to the line to determine the correlated X-axis value.
- The X-value will be the estimated kd .
Don’t forget the unit for the kd value
kd
A value which equates to the affinity of a binding interaction. The affinity is also determined by the dissociation constant (KA). A lower KA equates to a higher affinity
- Low kd = HIGH AFFINITY
- High kd = LOW AFIINITY
PA2
The pA2 value indicates the concentration of antagonist when double the agonist is required to have the same effect on the receptor as when no antagonist is present
PA2 = -log( conc. of antagonist added )
Tachyphylaxis
The progressive decrease in effect of medication from repetitive dose administration due to the related receptors being already occupied causing receptor desensitization.
Is a type of acute tolerance
Factors that can influence the response of a drug in patients
- Age
- Gender
- Ethnicity
- underlying medical conditions
- Medicine history
- Medicine being taken
- Diet
Efficancy
The ability of a drug-receptor complex to produce its desired effect.
It is the maximal effect acquired if a maximal dose is given.
TRUE OR FALSE
The EC50 does not change between lines in irreversible competitive antagonist.
TRUE
TRUE OR FALSE
In the presence of a reversible competitive antagonist the agonist log-concentration curve shifts to the left
FALSE
It shifts to the right without a change to the slope or maxinum effect.
Drug A has a pA2 of 8.
Drug B has a pA2 of 3.
Which one is more potent as an antagonist?
Drug A | pA2=8
The higher the pA2 the more potent the antagonist is.
Partial agonist
A ligand that binds to the receptor causing a response but with a low efficancy.
