chapter 9 Acid base Flashcards
1
Q
What is the pH scale based off of?
A
self-ionization of water
2
Q
what is the equation that defines pH?
A
pH=-log[H+]
3
Q
What is the pH of neutral, acidic, and basic solutions?
A
pH of 7 is neutral
below 7 is acidic
above 7 is basic
4
Q
Chemical substance that donates a H+ is known as?
A
Acid
5
Q
Chemical substance that accepts a H+?
A
Base
6
Q
Proton donor is known as?
A
an acid
7
Q
Proton acceptor is known as?
A
Base
8
Q
Examples of strong acids?
A
HCl, H2SO4, HNO3
9
Q
Examples of strong Bases?
A
NaOH, KOH, Ca(OH)2
10
Q
what is the main difference in defining a strong acid or base from a weak acid or base?
A
Strong acids or bases will completely dissociate (100%) in water.
Weak acid or base will only partially dissociate in water.
11
Q
what does A- stand for?
A
ionized form of an acid
12
Q
what does HA stand for?
A
non-ionized form of an acid
13
Q
what does BH+ stand for?
A
ionized form of a base
14
Q
what does B stand for?
A
non ionized form of a base
15
Q
what form of an acid or base can pass through the lipid bi layer?
A
non-ionized form of an acid or base
16
Q
what form of an acid or base can NOT pass through a lipid bi layer?
A
ionized form
17
Q
List 6 common weak acids that are medications.
A
Thiopental Barbiturates Phenobarbital Methotrexate TCAs Aspirin
18
Q
List 4 common weak bases that are medications.
A
Local anesthetics: Lidocaine
Amphetamine
Morphine
19
Q
Most drugs are either weak acids or bases or strong acids or bases?
A
most drugs are weak acids and weak bases.
20
Q
Do you want a drug which is stored for use in an ionized or non ionized form?
A
ionized, this equals water solubility and you can control the drug more in this form.
21
Q
HA represents what kind of drug?
A
Acidic drug
22
Q
if an acidic drug (HA) releases a proton (H+) what will it then cause to form?
A
anion (A-) to form
23
Q
B represents what kind of drug?
A
Basic drug
24
Q
if a basic drug (B) accepts a proton (H+) what does it then cause to form?
A
cation (BH+) to form
25
is the ionized charged form or a drug water or lipid soluble?
water soluble
26
what type of drug can cross the lipid bi layer, water or lipid soluble?
lipid soluble can cross the bi layer, that would also be non- ionized form of a drug.
27
match the following terms to one another.
water soluble
non ionized form
lipid soluble
ionized form
ionized form = water soluble
non ionized form= lipid soluble
28
another way to say lipid soluble is to say?
water insoluble
29
if something is water insoluble what does that mean in relation to crossing the cell membrane?
water insoluble means it CAN cross the cell membrane because it is lipid soluble.
30
if a drug is lipid insoluble what does that mean?
lipid insoluble means water soluble and thus it can NOT cross the cell membrane.
31
Degree of ionization of a drug depends on two things?
pH and pKa
32
the environment in which the drug is present is known as the?
pH
33
ionization constant of the drug is known as?
pKa
34
When pH < pKa?
increased HA and BH+ predominate.
35
When pH > pKa?
increased A- and B predominate.
36
Distribution of a drug between its ionized and non-ionized forms depends on the?
pH and pKa
37
the pH at which 50% of drug is ionized and 50% in non-ionized is known as what?
pKa
38
When pH = pKa what else is = to one another?
HA=A- and
| BH+ = B
39
Acidic drug + acidic media yields?
Non-ionized form (lipid soluble)
40
Acidic drug + basic media yields?
Ionized form (water soluble)
41
Basic drug + basic media yields?
Non-ionized form (lipid soluble)
42
Basic drug + acidic media yields?
Ionized form (water soluble)
43
When the pH of a weak acid increases, it then becomes more what?
It is moving towards alkaline, thus becoming more ionized.
44
When the pH of a weak acid decreases, it becomes more what?
if the pH is decreasing then it is becoming more acidic, and since it is already a weak acid it will become more non-ionized (which means more lipid soluble)
45
Ionized form of any drug is more soluble in water or lipids?
ionized = water soluble
46
With a weak acid, as the pH increases what happens to the solubility?
the solubility (water solubility) increases
47
with a weak acid as the solubility decreases what direction would the pH be moving?
the pH would be decreasing to decrease the solubility
48
in regards to a weak acid is solubility and pH proportional or inversely proportional?
pH and solubility are directly proportional with weak acids.
49
would a weak acid be mixed and stored in a high pH or low pH solution?
high pH solution (basic) in order to render the drug more neutral, ionic, water soluble.
No precipitate will form.
50
Weak base, what pH solution would you mix it with to make it more non ionized?
a higher pH solution. It is already a base, thus mixing it with a more alkaline solution will make the drug more non-ionized = lipid solubility.
51
weak base becomes more ionized when you do what to the pH?
decrease the pH, make it more acidic
52
how would you want to mix a weak base in order to increase its water solubility?
mix the weak base with an acid to make it more ionized.
53
in relation to a weak base, is solubility and pH directly proportional or inversely proportional?
inversely proportional. To increase solubility you decrease pH and vice versa.
54
why is it important to have a drug stored in its ionized form?
to not cause precipitation
55
mix with opposite means what?
if you have a weak acid or base you want to mix it for storage with the opposite pH solution in order to create a more ionic solution and have it be water soluble and not form a precipitate.
56
what will ionized diffuse through and what will non-ionized diffuse through?
ionized will diffuse through anything water soluble.
Non ionized will diffuse through anything lipid soluble.
57
When is a system said to be in a state of equilibrium?
when there is a balance between reactants and products
58
What defines the balance?
Thermodynamics
59
Does a forward reaction have to be equal to a backward reaction?
Yes
60
the numerical description of that balance is known as?
the equilibrium constant
61
law of equilibrium is also known as?
Le Chatelier's Principle
62
tell me the four points of Le Chatelier's Principle?
a. When a system in a state of dynamic equilibrium is disturbed, it will react to re-establish the equilibrium condition.
b. Nature likes being in an equilibrium state (homeostasis)
c. Changing reaction conditions (concentrations, temperature, etc.) moves the system away from being at equilibrium.
d. The system will adjust (go forward or backward) until it again is in an equilibrium state.
63
if you add products what will the equilibrium do?
shift towards the reactants. (filling the void)
64
if you remove products, the equilibrium will?
shift towards the products. (fill the void)
65
in what kind of reaction is heat a product? (produced)
exothermic reaction
66
in what kind of reaction is heat a reactant? (added in)
endothermic reactions
67
what type of process is favored with increasing temperatures?
endothermic process, when you increase a temp you are adding heat.
68
what state of matter has to be in the equilibrium reaction for a change in volume to be impacted?
GAS
Solids and liquids are not compressible
69
Decreasing volume favors the smaller or larger number of gas particles?
smaller number of gas particles. (more reactions can occur in a smaller volume)
70
What is Hbarb?
non-ionized or lipid-soluble form of barbiturate. This from can cross the cell membrane and readily absorb.
71
What is Barb-
ionized or water-soluble form of barbiturate. This form cannot cross the cell membrane and not readily absorb.
72
what denotes ionization?
a charge, thus if any letter or word has a charge associated then it is ionized.
73
What happens when a patient has acidosis and takes a weak acid barbiturate such as thiopental?
Weak acid mixed with acidic solution means more non-ionized drug to absorb into lipid bi-layers thus more drug absorbed (non-ionized portion) throughout.
74
weak acid drug mixed with acidic solution, which way will the reaction shift?
shift backwards forming more non-ionizing form.
75
acid + acid =?
Non-ionized
76
weak acids (thiopental) and other barbiturates partially dissociate to give off H+ (proton doner), what does that do the overall pH?
decreases the pH
77
what happens when a patient has alkalosis and takes a weak acid drug?
the weak acid becomes more ionized (decreasing H+, and thus increasing the pH)
78
if a weak acid drug is mixed with a patients alkalotic pH which way will the reaction shift?
shift forward forming more ionized form of the drug.
79
does ionized drug form absorb into the cells?
ionized drug form will not absorb
80
acid + base =?
ionized
81
Weak bases (local anesthetics) accept what?
H+
82
LA + H+ yields what?
LAH+
83
non-ionized or lipid-soluble form of local anesthetic. This from can cross the cell membrane and readily absorb.
What is it?
LA
84
ionized or water-soluble form of local anesthetic. This form cannot cross the cell membrane and not readily absorb.
What is it?
LAH+
85
If a patient has acidosis and you give them a LA what will occur?
weak base becomes more ionized when the patient has acidosis (increased H+, decreased pH)
86
a reaction that shifts forward forms more what? ionized or non ionized form?
more ionized form
87
if you mix an acid with a base then which way will the reaction shift? (this is the case with LA and an acidic patient)
shift forward
88
what form is not absorbed by the cells, ionized or non ionized?
ionized form is not absorbed through the lipid bilayer.
89
patient has alkalosis and you give them a LA , what happens?
weak base becomes more non - ionized
90
which way will the reaction shift if you give a LA to an alkalotic patient?
the reaction will shift backwards.
91
what form of a drug will absorb rapidly?
non-ionized
92
Tell me what pH solution you would mix with a LA in order to have it absorb rapidly inside the body?
A basic solution, high pH
93
when pH = pKa how much of the drug is ionized and non ionized?
50/50
94
if thiopental with a pH of 7.6 is mixed with a pH of 7.4 then what will occur to the ionized and non ionized portion?
more of the drug will become non-ionized and less of the drug will be ionized.
this is because you are mixing a weak acid with a slightly acidic solution, acid + acid = more non-ionized drug form.
95
what form of a drug do you want in the body in order to absorb? Is this what you want in a bag during storage? why?
in the body you want non-ionized so the drug can pass through lipid bilayer of the cell.
In a storage bac you want ionized form of a drug so that precipitate is not formed when mixed with water.
96
Why do you not want the non-ionized form of a drug during storage?
when the non-ionized form is dissolved in water a precipitate will form.
97
what form of the drug do you want it to be in during storage?
IONIZED- WATER SOLUBLE
98
Induction of thiopental (weak acid) be faster if the patient is acidotic or alkalotic?
It will be faster if the patient is acidotic.
| weak acid with acid = more non ionized form thus it can cross into the cell and work quicker. cross BBB
99
Should you mix thiopental with acidic (low pH) solution?
No, Thipental a weak acid should be mixed with a basic solution for storage, this stops precipitate from forming.
100
Why is thiopental is mixed and stored in a solution with pH = 10-11?
To increase the ionized form of the drug and prevent a precipitate from forming.
101
you store drug forms in the same or opposite pH?
store in OPPOSITE
102
What happens when lidocaine is injected into the body at pH=7.4?
Lidocaine is a weak base with a pH of 7.7, thus if injected into a solution that is 7.4 (acidic) more ionized form will be present thus less of the drug will cross the lipid bi-layers and less absorbed readily.
103
what does ionized or non ionized form have to do with a fetus?
non ionized portions of drugs can be transferred across the placenta to fetus.
104
mom pH vs fetal pH?
mom typically 7.4 and fetus is typically 7.2
105
Tell me what fetal ion trapping is?
When a drug enters mom's blood stream and is or becomes non-ionized it can then cross into the fetus via the placenta. Once with the fetus who is more acidic than mom the drug form will change to ionized and then can not cross back out of the placenta, thus "fetal ion trapping." the more acidic the fetus the more ion trapping the more circulation of the drug and the more fetal toxicity.
106
LA and fetal ion trapping?
LA 7.7, mom 7.4, fetus 7.2
thus whatever portion left in mom that is non ionized can still cross to the fetus (about 24%) and then become trapped and cause drug toxicity.
107
ionized or non ionized drug is excreted in the urine?
typically ionized is trapped and can not be reabsorbed back into the blood and is then excreted in the urine (ion trapping)
108
ionized or non ionized, which are freely filtered?
BOTH
109
If you have an overdose of a weak acid what would you give to someone to try and make them urinate it out?
something to make their urine basic, to trap the acid drug.
| treat overdose of acidic drug with Sodium bicarbonate
110
what is urine alkalization or acidification?
treating someone with an overdose of an acid or basic drug form with the opposite pH in order to have them urinate the drug out.
111
examples of weak acids that trap in basic envioroments?
phenobarbital, methotrexate, TCAs, aspirin
112
what would you give to someone to treat an overdose with a basic drug?
give them an acidic med to acidify the urine
| treat OD with ammonium chloride (NH4CL)
113
Example of a weak base drug overdosed on commonly?
amphetamines
114
the trapped portion of the chemical equation is?
the drug portion that has a charge, bc a charge denotes ionization and thus excretion.
115
is lipid soluble or nonlipid soluble drug reabsorbed by the kidney tubules?
lipid soluble is reabsorbed and to be lipid soluble you must be non ionized.
116
Aspirin is a weak acid or base?
weak acid
117
what form of an acid can back diffuse from urine to blood?
HA form bc that is the non ionized form.
118
what would you alkalinize the urine with?
NAHCO3
119
if the urine was alkaline (you gave sodium bicarb) with an aspirin OD, what form of the acid would then predominate and what does that then cause?
the ionized (A-) would predominate, there would be less back diffusion, more trapping and more excretion of the drug in urine.
120
What would happen if you acidify the urine of someone who has an aspirin OD?
The urine would be more acidic, HA form predominates, there is more back diffusion and less excretion of the weak acid.
121
if someone OD with amphetamine what would you use to treat?
Ammonium chloride - NH4Cl would acidify the urine.
122
Morphine is a weak base, how would you treat an OD in relation to excretion?
give something to acidify the urine (create more ionized form of the morphine), thus give ammonium chloride.
123
If a patient has cirrhosis they can not metabolize base thus what levels increase?
NH3 levels increase
124
where is NH3 absorbed and what does it cause?
absorbed in the gut and can cause toxicity
125
How would you treat a patient who has elevated NH3 levels? and why does this work?
give lactulose, it will convert into lactic acid.
acid + base = ionized form NH4+
the ionized form is traped and excreted from the gut.
