NBME PHARMACOLOGY REVIEW
2025 QUESTIOSN AND ANSWERS
Define Km in MM kinetics: - ....ANSWER ...-The concentration of
substrate [S] at which 1/2 Vmax is reached
Km is _________ related to affinity of the enzyme for its substrate -
....ANSWER ...-inversely
Vmax is directly proportional to what? - ....ANSWER ...-to the enzyme
concentration
What characterizes MM kinetics? - ....ANSWER ...-a hyperbolic curve when
Vmax is plotted against [S]. Most enzymes follow MM kinetics.
Enzymatic reactions demonstrated a sigmoid curve usually denote: -
....ANSWER ...-cooperative binding / kinetics, ie hemoglobin
In the lineweaver-burk plot, how is the y-intercept related to Vmax? What does the
slope of the line equal? The y-intercept? The x-intercept? - ....ANSWER ...-
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 1
,They're inversely related. The slope of the line is equal to Km/Vmax while the y-
intercept is equal to 1/Vmax. The x-intercept is equal to 1/-Km.
In the L-B plot, if the x-intercept is closer to 0, what does that mean? -
....ANSWER ...-x-intercept = 1/-Km. So if it is closer to 0, Km is greater
and affinity is lower
In the L-B plot, how are competitive and non-competitive inhibitors expressed
with respect to one another? - ....ANSWER ...-competitive inhibitors' lines
cross eachother competitively whereas non-competitive do not.
What are some key differences between competitive and non-competitve
inhibitors? - ....ANSWER ...-competitive=reversible or irreversible. non-
competitive=irreversible. competitive may be overcome by a higher [S] whereas
noncompetitive or irreversible competitive may not be overcome. Noncompetitive
inhibitors do not resemble substrate, and they do not bind the active site like the
other two. Reversible competitive has no effect on Vmax whereas the other two
lower it. Conversely, reversible competitive increases the Km whereas the other
two have no effect on Km. pharmacodynamically, reversible competitive inhibitors
lower potency whereas the other two lower efficacy.
Define pharmacokinetics: - ....ANSWER ...-The effects of the body on the
drug. ADME.
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,Define pharmacodynamics: - ....ANSWER ...-Effects of the drug on the
body. Includes receptor binding, drug efficacy, drug potency and drug toxicity
Define Bioavailability (F): - ....ANSWER ...-The fraction of the administered
drug which reaches systemic circulation unchanged. For an IV dose, the F=100%.
Orally it is typically less because of incomplete absorption and / or FPHM.
Define Volume of Distribution (Vd): - ....ANSWER ...-The theoretical
volume occupied by the total absorbed drug amount at the plasma concentration.
Apparent Vd of plasma protein: - ....ANSWER ...-bound drugs can be
altered by liver and kidney disease (low protein binding, high Vd). Vd=amount of
drug in body / plasma concentration of drug
Where is Vd low? - ....ANSWER ...-In blood. 4-8L. Drug types: large /
charged molecules, plasma protein bound.
Where is Vd medium? - ....ANSWER ...-ECF. Small hydrophilic molecules.
Where is Vd high? - ....ANSWER ...-All tissues including fat. Small lipophilic
molecules, especially if bound to tissue protein.
What is the equation for half-life? - ....ANSWER ...-T1/2= .693 x Vd / CL.
T1/2 is a property of _______ order elimination - ....ANSWER ...-first
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, How many half lives does it take for a drug administered as a constant infusion to
reach steady state? - ....ANSWER ...-4-5
How many half lives does it take for a drug administered as a constant infusion to
reach 90% of steady state? - ....ANSWER ...-3.3
Define clearance (CL): - ....ANSWER ...-The volume of plasma cleared of a
drug during a given time unit.
Under what circumstances may clearance be impaired? - ....ANSWER ...-
cardiac, hepatic or renal defects
What is the equation for clearance? - ....ANSWER ...-CL=rate of elimination
of drug / plasma drug concentration. This is = Vd x Ke (elimination constant)
How do you calculate loading dose? - ....ANSWER ...-= Cp x Vd / F (where
Cp=target plasma concentration at steady state)
How do you calculate maintenance dose? - ....ANSWER ...-= Cp x CL x T /
F (T=tau=dose interval, or time between doses, if it is not administered
continuously)
What happens to loading and maintenance doses during renal and liver disease? -
....ANSWER ...-maintenance dose is lowered whereas loading dose remains
unchanged
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 4
2025 QUESTIOSN AND ANSWERS
Define Km in MM kinetics: - ....ANSWER ...-The concentration of
substrate [S] at which 1/2 Vmax is reached
Km is _________ related to affinity of the enzyme for its substrate -
....ANSWER ...-inversely
Vmax is directly proportional to what? - ....ANSWER ...-to the enzyme
concentration
What characterizes MM kinetics? - ....ANSWER ...-a hyperbolic curve when
Vmax is plotted against [S]. Most enzymes follow MM kinetics.
Enzymatic reactions demonstrated a sigmoid curve usually denote: -
....ANSWER ...-cooperative binding / kinetics, ie hemoglobin
In the lineweaver-burk plot, how is the y-intercept related to Vmax? What does the
slope of the line equal? The y-intercept? The x-intercept? - ....ANSWER ...-
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 1
,They're inversely related. The slope of the line is equal to Km/Vmax while the y-
intercept is equal to 1/Vmax. The x-intercept is equal to 1/-Km.
In the L-B plot, if the x-intercept is closer to 0, what does that mean? -
....ANSWER ...-x-intercept = 1/-Km. So if it is closer to 0, Km is greater
and affinity is lower
In the L-B plot, how are competitive and non-competitive inhibitors expressed
with respect to one another? - ....ANSWER ...-competitive inhibitors' lines
cross eachother competitively whereas non-competitive do not.
What are some key differences between competitive and non-competitve
inhibitors? - ....ANSWER ...-competitive=reversible or irreversible. non-
competitive=irreversible. competitive may be overcome by a higher [S] whereas
noncompetitive or irreversible competitive may not be overcome. Noncompetitive
inhibitors do not resemble substrate, and they do not bind the active site like the
other two. Reversible competitive has no effect on Vmax whereas the other two
lower it. Conversely, reversible competitive increases the Km whereas the other
two have no effect on Km. pharmacodynamically, reversible competitive inhibitors
lower potency whereas the other two lower efficacy.
Define pharmacokinetics: - ....ANSWER ...-The effects of the body on the
drug. ADME.
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 2
,Define pharmacodynamics: - ....ANSWER ...-Effects of the drug on the
body. Includes receptor binding, drug efficacy, drug potency and drug toxicity
Define Bioavailability (F): - ....ANSWER ...-The fraction of the administered
drug which reaches systemic circulation unchanged. For an IV dose, the F=100%.
Orally it is typically less because of incomplete absorption and / or FPHM.
Define Volume of Distribution (Vd): - ....ANSWER ...-The theoretical
volume occupied by the total absorbed drug amount at the plasma concentration.
Apparent Vd of plasma protein: - ....ANSWER ...-bound drugs can be
altered by liver and kidney disease (low protein binding, high Vd). Vd=amount of
drug in body / plasma concentration of drug
Where is Vd low? - ....ANSWER ...-In blood. 4-8L. Drug types: large /
charged molecules, plasma protein bound.
Where is Vd medium? - ....ANSWER ...-ECF. Small hydrophilic molecules.
Where is Vd high? - ....ANSWER ...-All tissues including fat. Small lipophilic
molecules, especially if bound to tissue protein.
What is the equation for half-life? - ....ANSWER ...-T1/2= .693 x Vd / CL.
T1/2 is a property of _______ order elimination - ....ANSWER ...-first
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 3
, How many half lives does it take for a drug administered as a constant infusion to
reach steady state? - ....ANSWER ...-4-5
How many half lives does it take for a drug administered as a constant infusion to
reach 90% of steady state? - ....ANSWER ...-3.3
Define clearance (CL): - ....ANSWER ...-The volume of plasma cleared of a
drug during a given time unit.
Under what circumstances may clearance be impaired? - ....ANSWER ...-
cardiac, hepatic or renal defects
What is the equation for clearance? - ....ANSWER ...-CL=rate of elimination
of drug / plasma drug concentration. This is = Vd x Ke (elimination constant)
How do you calculate loading dose? - ....ANSWER ...-= Cp x Vd / F (where
Cp=target plasma concentration at steady state)
How do you calculate maintenance dose? - ....ANSWER ...-= Cp x CL x T /
F (T=tau=dose interval, or time between doses, if it is not administered
continuously)
What happens to loading and maintenance doses during renal and liver disease? -
....ANSWER ...-maintenance dose is lowered whereas loading dose remains
unchanged
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 4
