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PDA Test 2 > Physical Properties 2 Lecture > Flashcards

Physical Properties 2 Lecture Flashcards

1
Q

Log P is

A

partition coefficient

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2
Q

clogP

A

calculated partition coefficient

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3
Q

LogD

A

Distribution coefficient

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4
Q

Define lipophilicty

A

Fat-liking

Decrease lipophilicity, increase hydrophilicity

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5
Q

Define ionized

A

water soluble, not very lipophilic because it forms strong H bonds

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6
Q

Hydrophobic bonding is?

A

Drugs are typically hydrophobic molecules
Binding sites = hydrophobic too
Like attracts like

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7
Q

What drives hydrophobic bonding?

A

Proximity and H or ionic bonding
Anchorage
Entropy gains (when water molecules are displaced from the active site)

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8
Q

Enthalpy gains may result from?

A

van der Waals bonding between: alkyl, aryl or halogen groups & pi-pi stacking (phenol rings)

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9
Q

Define Entropy gains

A

Increased disorder
Gains energy
Achieved when water is displaced form the active site
Favors hydrophobic interactions bc it allows more disorder

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10
Q

Gibbs Free Energy equation?

A

Delta G = delta H - T*delta S
Delta G: free energy the system has
Delta H: change in enthalpy
Delta S: Entropy

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11
Q

Negative delta S means?

A

Increased order (reduced entropy)

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12
Q

Negative delta G means?

A

gains energy

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13
Q

Nonpolar surface into water?

A

Disturbs network of water-water H bonds
Causes reorientation of the network of H bonds to give fewer but stronger, water-water H bonds close to the nonpolar surface

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14
Q

Lower IC50 means?

A

more active the compound (lipophilicity increases)

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15
Q

What is the hydrophobic effect?

A

Compound is too lipophilic, so it may be insoluble in aqueous media, bind too strongly to plasma protein (no desired effect), distribute into lipid bilayers and unable to reach the inside of the cell
Compound is too polar, it may no absorbed through the gut wall due to lack of membrane solubility

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16
Q

Define logP

A

measure of the relative affinity of a molecule for the lipid and aqueous phases in the absence of ionisation
MEASURE OF NEUTRAL COMPOUNDS

17
Q

1-Octanol is a frequent lipid phase because?

A

It has polar and nonpolar regions
P is fairly easy to measure and often correlates well with biological properties
Predicted fairly accurately using computation models

18
Q

As logP increases…?

A

lipophilicity increase, hydrophobicity increases, more chances of van der Waals interactions
Increase binding to enzyme/receptor
Increased absorption through membrane
Less free drug to act

19
Q

Define distribution coefficient

A

Effective lipophilicity of an ionized compound at a given pH
Change pH = change logD
Increased ionization = decrease logD
Low logD = water soluble
High logD = not water soluble, hydrophilic, ionized species, acid

20
Q

Distribute into octanol?

A

NO IONIZED COMPOUNDS

21
Q

pH behavior with amphoteric drugs?

A

Low pH: OH stays but proton added to the amine

As pH increases: more alkaline –> OH gives away H (ionized species)

22
Q

Increasing logD?

A 
Increase lipophilicity (stronger binding)
Decrease water solubility (can't get into the circulation)
Decrease ionization
23
Q

Add oxygen to a molecule ALWAYS?

A

decrease lipophilicity because of HBA –> H bond with water –> more soluble

24
Q

Add a CF3 group to a molecule?

A

Increase lipophilicity

25
Q

Replacing H with a halogen?

A

Increases the lipophilicity

26
Q

Addition of a hydroxyl group

A

Decreases the lipophilicity

27
Q

Removal of the quinoline N to give a carboxcyclic ring

A

Greatly increases lipophilicity

28
Q

Replacing a quinoline with a benzene ring will?

A

Increase the lipophilicity

29
Q

What increase lipophilicity?

A 
Methyl 
Ethyl
Higher order hydrocarbon
Trifluoromethane
Cl
Br
CH2Cl
C2H4Br
Phenyl rings
Carbocyclic rings
30
Q

Why is CF3 so lipophilic?

A

Cannot be ionized
F holds electrons so tight, can’t form H bonds
Extremely EWG, exert this effect across several bonds, to stabilize negative charge or prevent H bonding to a lone pair

31
Q

Structural features that reduce lipophilicity

A

Polar functional groups (contain electronegative atoms)

Groups that ionize (form stable anions and cations): OH, NH2, COOH, OMe, N(CH3)2, CONH2

PDA Test 2 (11 decks)

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