Exam 1 Material Flashcards
Any substance that brings about a change in biologic function through its chemical actions
Drug
To modulate the biological activity of a receptor, a drug needs to
move to the location of the receptor and bind to it
A similar structure motif that drugs bind to when they bind to the same target, set of features similar between a group of molecules
Pharmacophore
Examples of pharmacophore
Fentanyl, naloxone, morphine
Structure activity relationship
Structure determines activity, can determine binding and membrane permeability
Properties determined from structure
Stereochemistry, solubility, ionization, hydrophobicity, size
Properties that affect biological activities
Permeability, target binding, metabolism, excretion
Drug property affected by pH
ionization
Ionizable groups
Arylcarboxylic acid, arylamine, aromatic amine, alkyl carboxylic acid, alkyl amine, phenol, guanidine
Henderson hasselbach equation
pH=pKa+log [A]/[HA]
pH < pKa
protonated
pH > pKa
deprotonated
At pH 6.4 what is the ratio of drug in acid form to base form? pKa is 4.4
6.4=4.4+Log A/HA
=2 move 2 zeros
1:100
deprotonated, more base than acid
Modes of drug permeation into body
Intercellular junctions
Lipid cell membranes
Transporters
Endocytosis
Exocytosis
Hydrophilic groups
Alcohol, carboxylic acid, amine, ketone, amide, ester
Hydrophobic
Methyl, chloro, phenyl, hexyl, cyclohexyl
Less OH means more
hydrophobic
H bond donors
OH, NH
H bond acceptors
O, N
Lipinski’s rule of 5
Describes orally active drugs
No more than 5 H bonds
No more than 10 H acceptors
Molecule mass less than 500
LogP under 5
Predict effect of a structural change in a drug on its solubility in water
Lose OH, may no longer be soluble/orally active
LogP <0 favors ?
Water
LogP = 0 ?
Equal distribution
LogP > 0
Favors 1 octanol
bigger logP means
More hydrophobic
Explain why the relationship of drug effectiveness vs LogP is parabolic
Lipophilicity improves drug permeation but too much may hinder crossing
Calculate ClogP
Sum of Pi values
lower number means more acidic
Estimate LogD
LogD = LogP - (pH-pKa)
When pH is bigger than pKa it is first in equation
When are drugs most absorbed?
Where they are mostly neutral
Location with pH of 5-7
jejunum and duodenum