Ionization Of Drugs Flashcards
When something is non-ionized, what does this mean?
It is not charged
When something is ionized, what does this mean?
It is charged
Which drugs cross the membrane easier, ionized or non-ionized?
Non-ionized (uncharged)
In regards to acids and bases, what are most drugs?
Weak acids or weak bases
If you have a drug that is either a weak acid or a weak base, what can happen to it?
It can be ionized (influenced by pH)
If you have a hydrogen attached to an acid, what form is it in?
Non-ionized (no charges)
If you have an acid with no hydrogen attached to it, what form is it in?
Ionized (charged)
If you have a hydrogen attached to a base, what form is it in?
Ionized (charged)
If you have a base with no hydrogen attached to it, what form is it in?
Non-ionized (no charges)
In what type of pH environments are there lots of hydrogens?
Low pH (acidic)
Constant pH for a drug, where 50% is ionized and 50% is non-ionized
pKa
Where do you draw the divider line in order to see pKa?
Right down the arrows dividing the 2 sides of the equations
If you have a drug that is HA, in what type of pH environment will it be in?
Acidic (lots of hydrogens want to bind to the weak acid)
Using the terms relatively loosely, what does the term basic mean?
Above the drugs pKa
Using the terms relatively loosely, what does the term acidic mean?
Below the drug’s pKa
Which forms of the acid and base will penetrate the cell membrane?
HA (uncharged weak acid)
B (uncharged weak base)
Which forms of the acid and base will not penetrate the cell membrane?
A- (charged weak acid)
BH+ (charged weak base)
The lower the pKa, the stronger the _____?
Acid
The higher the pKa, the stronger the _____?
Base
Example:
Here’s a drug who’s a weak acid, and it’s pKa is 5.0. If the drug is placed in a pH of 7.0, the major form of this drug is what?
A- (charged, ionized, weak acid)
Because the pH is greater than the pKa, it will be on the basic side of things.
Example:
Here’s a drug who’s a weak acid, and it’s pKa is 5.0. If the drug is placed in a pH of 7.0, the major form of this drug is A- (charged, ionized, weak acid). Is this drug going to easily move in the body?
No because it is charged and cannot pass the membrane
What is the equation for Henderson-Hasselbalch?
pH - pKa