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Med Chem Midterm > Lecture 3 cont > Flashcards

Lecture 3 cont Flashcards

1
Q

Neutral fats make up ____-____% of body weight

A

20-50%

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2
Q

the more lipophilic the drug, the ____ likely it will deposit in neutral fats

A

MORE

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3
Q

what are the mechanisms in which lipophilic drugs deposit in neutral fats?

A

either:

  1. Direct physical dissolution
  2. primary deposition into membranes, follows by slow redistribution into fatty tissue
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4
Q

give an example of drugs that get deposited into neutral fats.
what is the effect of this?

A

ultra short acting barbiturates (such as thiopental)

thus, these drugs have a VERY SHORT DURATION OF ACTION because they are deposited into these neutral fats, thus decreasing its plasma concentration below therapeutic levels.

this could be intentional

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5
Q

does sulfur increase or decrease lipophilicity

A

in organic molecules, sulfur INCREASES lipophilicity (except when bound to hydrogen)

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6
Q

what is thiopental

A

a sulfur containing, ultra short acting barbiturate that gets deposited into neutral fats, thus having a very short duration of action

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7
Q

what does QSAR stand for

A

quantitative structure-activity relationship

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8
Q

QSAR studies were originally performed by whom and when

A

Hansch in the 1960s

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9
Q

true or false

QSAR studies began in the 1960s and are still evolving

A

true

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10
Q

Hansch performed studies to correlate what?

A

he wanted to correlate the CHEMICAL STRUCTURE and PHYSICAL PROPERTIES of the drug to its biological activity

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11
Q

what is THF

A

Tetrahydrofuran – an organic solvent

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12
Q

What does LD50 mean

A

the dose at which 50% of the test sample is killed. Lethal dose

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13
Q

what is ED50

A

effective dose – the dose at which 50% of the population gets treated effectively

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14
Q

give the formula for the rate of the drug response, according to QSAR

A

Rate of response = d[Response]/dt = ACkx

A = probability of molecule reaching the site of action
C = extracellular drug concentration
Kx = rate (or equilibrium) constant

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15
Q

in QSAR, what are the 3 parameters used to correlate the chemical structure, physical properties, and biological activities of a drug?

A

-lipophilic parameter (pi)
-electronic parameter (sigma)
-steric parameter (Es)

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16
Q

what does the lipophilic parameter (pi) of QSAR indicate?

A

the relative lipid solubility

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17
Q

a positive p value in QSAR indicates what?

A

a positive p value means that the substituent will cause an increase in lipid solubility

18
Q

give the equation of QSAR

A

Log 1/C (A) = -k(pi) squared + k’pi + p sigma + k”

A= probability of the molecule reaching the site of action
C = extracellular drug concentration
pi = lipophilic parameter
sigma = electronic parameter

19
Q

in the QSAR formula:

log1/C (A) = -kpi^2 + k’pi + psigma + k”

which are variables?
which are constants?

A

constants = k, k’, k”, p
variables = pi, sigma

20
Q

Hansch proposed his equations to measure the ___, ____, and ___ contributions when a molecule is…..

this is helpful for what?

A

Hansch proposed his equations to measure the LIPOPHILIC, ELECTRONIC, AND STERIC contributions when a molecule is SUBSTITUTED BY VARIOUS GROUPS.

this is helpful in drug design

21
Q

Alkyl (–R) and Alkoxy (R–O) are typically electron withdrawing or donating?

A

donating

22
Q

what is a nitrile group

are they electron donating or withdrawing?

A

R-C triple bond N

the most electron withdrawing group

23
Q

are halogens electron donating or withdrawing?

name the halogens

A

withdrawing

fluorine
chlorine
bromine
iodine
astatine
teenessine

24
Q

what is an alkoxy group?

are they electron donating or withdrawing?

A

donating

alkyl with a single bond to oxygen

25
Q

amine groups are electron donating or withdrawing?

A

donating, as long as it doesnt become protonated in aliphatic/aprotic conditions

26
Q

the lipophilic parameter gives what?

A

the relative lipid solubility

27
Q

what is the rate limiting condition for a drug to reach the site of action?

A

movement through a series of membranes

28
Q

since the rate limiting conditions for reaching the site of action involves movement through a series of membranes, _______ has become the most important physiochemical measurement for QSAR studies

A

PARTITION COEFFICIENT

29
Q

what value is the “relative lipid solubility profile”

A

partition coefficient

30
Q

p substituent=…….

a positive p value means what?

A

p substituent = log PC (substituent molecule) - log PC (parent molecule)

a positive p value means the substituent will cause in INCREASE IN LIPID SOLUBILITY

31
Q

True or false

when added as substituents, halogens cause a decrease in lipophilicity

A

FALSE

they actually contribute to lipophilicity a pretty substantial amount

32
Q

is carboxamide a polar or nonpolar substituent?

will in cause an increase or decrease in PC?

A

polar substituent. will cause a decrease in PC

33
Q

will COCH3 group cause increase or decrease in PC

A

decrease

COCH3 = acetyl

34
Q

will nitrile group cause increase or decrease in PC

A

decrease

CN

hydrophiliv

35
Q

will alkyl groups cause an increase or decrease in PC

A

increase

36
Q

true or false

the more carbons in an alkyl group, the more it will contribute to an increase in PC

A

true

37
Q

the lower the pi, the _____ hydrophilic

A

more

38
Q

the higher the sigma value, the more electron _____ it is

A

withdrawing

39
Q

the higher the ES, the ____ it is

A

larger

40
Q

when looking at QSAR and multiple formulas are generated with relatively the same correlation coefficients (r squared), which equation should you pick?

A

the shortest variable containing equation

41
Q

to obtain maximal activity……

A

maximize log A. use small, potent dose

42
Q
A

Med Chem Midterm (11 decks)

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