Ionization Of Drugs Flashcards

1
Q

When something is non-ionized, what does this mean?

A

It is not charged

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2
Q

When something is ionized, what does this mean?

A

It is charged

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3
Q

Which drugs cross the membrane easier, ionized or non-ionized?

A

Non-ionized (uncharged)

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4
Q

In regards to acids and bases, what are most drugs?

A

Weak acids or weak bases

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5
Q

If you have a drug that is either a weak acid or a weak base, what can happen to it?

A

It can be ionized (influenced by pH)

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6
Q

If you have a hydrogen attached to an acid, what form is it in?

A

Non-ionized (no charges)

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7
Q

If you have an acid with no hydrogen attached to it, what form is it in?

A

Ionized (charged)

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8
Q

If you have a hydrogen attached to a base, what form is it in?

A

Ionized (charged)

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9
Q

If you have a base with no hydrogen attached to it, what form is it in?

A

Non-ionized (no charges)

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10
Q

In what type of pH environments are there lots of hydrogens?

A

Low pH (acidic)

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11
Q

Constant pH for a drug, where 50% is ionized and 50% is non-ionized

A

pKa

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12
Q

Where do you draw the divider line in order to see pKa?

A

Right down the arrows dividing the 2 sides of the equations

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13
Q

If you have a drug that is HA, in what type of pH environment will it be in?

A

Acidic (lots of hydrogens want to bind to the weak acid)

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14
Q

Using the terms relatively loosely, what does the term basic mean?

A

Above the drugs pKa

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15
Q

Using the terms relatively loosely, what does the term acidic mean?

A

Below the drug’s pKa

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16
Q

Which forms of the acid and base will penetrate the cell membrane?

A

HA (uncharged weak acid)

B (uncharged weak base)

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17
Q

Which forms of the acid and base will not penetrate the cell membrane?

A

A- (charged weak acid)

BH+ (charged weak base)

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18
Q

The lower the pKa, the stronger the _____?

A

Acid

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19
Q

The higher the pKa, the stronger the _____?

A

Base

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20
Q

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

A- (charged, ionized, weak acid)

Because the pH is greater than the pKa, it will be on the basic side of things.

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21
Q

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?

A

No because it is charged and cannot pass the membrane

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22
Q

What is the equation for Henderson-Hasselbalch?

A

pH - pKa

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23
Q

Using the H-H equation, if you receive a negative number, what does this mean?

A

pH is less than pKa, meaning it is in an acidic environment

24
Q

Using the H-H equation, if you receive a positive number, what does this mean?

A

pH is greater than pKa, meaning it is in a basic environment

25
Q

Which form of weak acid easily passes the membrane?

A

HA

26
Q

Which form of weak base easily passes the membrane?

A

B

27
Q

What kind of solubility does a non-ionized (NI) drug have? What does this mean for the drug?

A

Lipid soluble

-this is why it moves easily in the body (wants to stay b/c it can move through the cell membrane)

28
Q

What kind of solubility does an ionized (I) drug have? What does this mean for the drug?

A

Water soluble

-more readily eliminated form the body because it can not pass the cell membrane

29
Q

Given an acid and a base, what forms are non-ionized?

A

HA and B

30
Q

Given an acid and a base, what forms are ionized?

A

A- and BH+

31
Q

Since pH is on a log scale, if you change pH by just 1 unit, how much are you changing the concentration of the drug?

A

By 10-fold

32
Q

If pH is less than pKa, what environment are you in?

A

Acid, relative to drug’s pKa

33
Q

If pH is greater than pKa, what environment are you in?

A

Basic, relative to drug’s pKa

34
Q

In a low pH environment, what would you expect to be the percent of non-ionized acid and base, and in which form?

A
HA = very high
BH+ = very low
35
Q

In a high pH environment, what would you expect to be the percent of non-ionized acid and base, and in which form?

A
A- = very low
B = very high
36
Q

Where the acid and base curves cross, what does it mean?

A

pH = pKa (50% ionized and 50% non-ionized)

37
Q

If you give a weak acid drug to a patient, where in their body will it absorb best?

A

Stomach (pH = 1)

38
Q

If you give a weak base drug to a patient, where in their body will it absorb best?

A

Small intestines (pH = 5-6)

39
Q

What is the pH of blood?

A

7.4

40
Q

What is the pH of urine?

A

5-8

41
Q

What is the pH of the stomach?

A

1

42
Q

What is the pH of the small intestines?

A

5-6

43
Q

Which forms of acids and bases will have a greater clearance (will be more easily cleared from the body)?

A

Ionized (charged) forms like HB+ and A-

44
Q

To get rid of a weak acid, what type of environment would you want to put it it?

A

Basic solution (closer to 8)

45
Q

To get rid of a weak base, what type of environment would you want to put it it?

A

Acidic solution (closer to 5)

46
Q

When pH is less than pKa, what forms of acid and base predominate, and are the protonated or deprotonated?

A

Protonated

HA and BH+

47
Q

When pH is greater than pKa, what forms of acid and base predominate, and are the protonated or deprotonated?

A

Deprotonated

A- and B

48
Q

Where will a drug go if you put it in it’s “like” environment? (Acid in an acidic environment)

A

It will stay in that environment

49
Q

Where will a drug go if you put it in it’s “un-like” environment? (Acid in a basic environment)

A

It will leave that environment

50
Q

If a patient has over-dosed on weak acid, what do you do for that patient?

A

Give them a fixed amount of sodium bicarb to manipulate the urine to make it closer to 8 (more alkaline) in order to get rid of the acid

51
Q

If a patient has over-dosed on weak base, what do you do for that patient?

A

Give them a fixed amount of ammonium chloride to manipulate the urine to make it closer to 5 (more acidic) in order to get rid of the base

52
Q

What drug do you use to treat hepatic enchephalopathy?

A

Lactulose

53
Q

What is lactulose converted to by the gut bacteria, when trying to treat hepatic encephalopathy?

A

Lactic acid

54
Q

When treating hepatic encephalopathy with lactulose, the acidic environment in the gut converts what to what?

A

In converts ammonia (NH3) to ammonium (NH4+)

55
Q

Why do you give a patient with hepatic encephalopathy lactulose?

A

The gut bacteria converts the intestinal tract to be acidic, so NH3 (ammonia) is converted into NH4+ (ammonium), which has a positive charge (ionized), meaning it is more easily eliminated from the body