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Pharmacology > Pharmacokinetics I > Flashcards

Pharmacokinetics I Flashcards

1
Q

How many half-lives does it take to reach steady state concentration or to eliminate the drug?

A

5 half-lives

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2
Q

What is the main goal when determining dose?

A

The goal is to determine the lowest effective dose (~68% of population)

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3
Q

What factors influence dose?

A 
Maturing organ function (BBB in children)
Age of the patient (decreased kidney
function, increased fat)
Organ pathology (Liver, Kidney, etc.)
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4
Q

What are other terms for “oral”

A

Enteral, PO

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5
Q

What is the most common, convenient, safest and economical method of drug administration?

A

Oral (enteral, PO)

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6
Q

What is the main disadvantage of oral drug administration?

A

First pass effect- the absorbed drug is exposed to the liver first

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7
Q

When are parenteral routes of administrations used?

A

Used when drugs cannot be administered orally

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8
Q

What is the most direct route of administration?

A

Injections

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9
Q

How are gaseous anesthetics, agents that readily vaporize, and aerosol drugs administered?

A

Inhalation

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10
Q

When is rectal drug administration used?

A

When oral ingestion is precluded by emesis (vomiting) or unconsciousness

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11
Q

Does buccal/sublingual drug administration have high or limited first pass effect?

A

Limited

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12
Q

Absorption of topical drugs is proportional to what?

A

The surface area exposed and lipid solubility of the drug

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13
Q

How do inflammation and conditions that increase cutaneous blood flow effect absorption?

A

Enhance absorption

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14
Q

What is absorption?

A

Process whereby a drug gains entry into bodily fluids, typically the blood, that distribute it throughout the organism.

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15
Q

Drugs that have a high degree of lipid solubility are most likely absorbed by which mechanism?

A

Simple diffusion

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16
Q

What mechanism of absorption do small, water soluble drugs; concentration gradients use?

A

Aqueous pores

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17
Q

What mechanism of absorption do drugs use when drugs get engulfed by vesiculation of cell membrane followed by endocytosis?

A

Vesicular transport

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18
Q

What factors modify absorption?

A 
Route of administration
Solubility (aqueous vs. oil)
Dissolution
Concentration of drug
Blood flow/Circulation
Absorbing surface area and contact time
pH
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19
Q

Are most drugs strong acids/ strong bases or weak acids/weak bases?

A

Weak acids or weak bases

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20
Q

Are acids proton donators/acceptors?

A

Proton donators (HA ↔ A- + H+)

21
Q

Are bases proton donators/acceptors?

A

Proton acceptors (B + H+ ↔ BH+)

22
Q

What affects a drug’s ability to permeate biological membranes and exert its effect?

A

Degree of ionization

23
Q

To cross a membrane, a drug must be what?

A

Non-ionized and lipid soluble

24
Q

Why are ionized drugs not able to be absorbed?

A

Ionized drugs are surrounded by a water molecules that increase
hydrophilicity and prevent it absorption

25
Q

What kind of acids/bases cannot be absorbed?

A

Strong acids and bases

26
Q

An acid in an acidic environment is what?

A

Non-ionized and readily absorbed

27
Q

A base in a basic environment is what?

A

Non-ionized and readily absorbed

28
Q

What is ion-trapping?

A

Acid in basic environment or base in acidic environment will become ionized and and will accumulate in that environemnt

29
Q

When an acid is pronated, is it ionized or non-ionized?

A

Non-ionized

30
Q

When a base is pronated, is it ionized or non-ionized?

A

Ionized

31
Q

In an acidic environment (stomach), a weakly acidic drug is predominately _____, more lipid soluble and _____ absorbed.

A

Non-ionized (protonated; HA)

Rapidly

32
Q

In a basic environment (intestine), a weakly acidic drug is predominately _____, and _____ absorbed.

A

Ionized (unprotonated; A-)

Not rapidly

33
Q

In an acidic environment (stomach), a weakly basic drug is predominately _____, and is _____ absorbed.

A

Ionized (protonated; BH+)

Not rapidly

34
Q

In a basic environment (intestine), a weakly basic drug is predominately _____, more lipid soluble and _____ absorbed.

A

Non-ionized (unprotonated; B)

Rapidly

35
Q

What can ion trapping be used for?

A

To increase the elimination of drugs

36
Q

If you make urine basic, ____ drugs will be trapped and excreted.

What can you use to make the urine more basic?

A

Acidic

Sodium bicarbonate or acetazolamide

37
Q

If you acidify the urine, ____ drugs will be trapped and excreted.

What can you use to make the urine more acidic?

A

Basic

Ammonium chloride

38
Q

What does the Henderson-Hasselbalch equation tell you?

A

Degree of ionization of weakly acidic or basic drug at different pHs

39
Q

What is pKa?

A

pH at which the amount of

ionized vs. non-ionized forms of a drug are equal

40
Q

If pH < pka

a) Does the protonated/unprotonated form dominate?
b) An acid will be ionized/non-ionized and rapidly/slowly absorbed
c) A base will be ionized/non-ionized and rapidly/slowly absorbed

A

a) Protonated
b) Non-ionized (HA), rapidly
c) Ionized (BH+), slowly

41
Q

If pH > pka

a) Does the protonated/unprotonated form dominate?
b) An acid will be ionized/non-ionized and rapidly/slowly absorbed
c) A base will be ionized/non-ionized and rapidly/slowly absorbed

A

a) Unprotonated
b) Ionized (A-), slowly
c) Non-ionized (B), rapidly

42
Q

Weak acid in acidic environment.
pKa = 5.4
pH = 4.4
What is A-/HA?

A

pH < pKa = Protonated dominates
More non-ionized (acid + protonated)
1 degree difference = 10 fold

A-/HA = 1 ionized/10 non-ionized

43
Q

Weak acid in basic environment.
pKa = 4.4
pH = 7.4
What is A-/HA?

A 
pH > pKa = Unprotonated dominates
More ionized (acid + unprotonated)
3 degree difference = 1,000 fold

A-/HA = 1,000 ionized/1 non-ionized

44
Q

Weak base in acidic environment.
pKa = 5.4
pH = 3.4
What is B/BH+?

A 
pH < pKa = Protonated dominates
More ionized (base + protonated)
2 degree difference  = 100 fold

B/BH+ = 1 non-ionized/100 ionized

45
Q

Weak base in basic environment.
pKa = 4.4
pH = 8.4
What is B/BH+?

A

pH > pKa = Unprotonated dominates
More non-ionized (base + unprotonated)
4 degree difference = 10,000

B/BH+ = 10,000 non-ionized/1 ionized

46
Q

Drug A is a weak organic acid, pKa = 6.4. What is the ratio of ionized to non-ionized drug in the urine with pH = 6.4?

A

1:1

47
Q

Drug B is a weak acid, pKa = 6.4. What is the ratio of non-ionized to ionized drug in the blood with pH = 7.4?

A 
pH > pka = Unprotonated dominates
More ionized (acid + unprotonated)
1 degree difference  = 10 fold

A- (ionized) / HA (nonionized) = 10/1
HA (nonionized) / A- (ionized) = 1/10

HA/A- ratio = 1:10

48
Q

Drug B is a weak base, pKa = 5.4. What is the ratio of non-ionized to ionized drug in the blood with pH = 7.4?

A

pH > pKa = Unprotonated dominates
More more non-ionized (base + unprotonated)
2 degree difference = 100 fold

B/BH+ ratio = 100:1

Pharmacology (25 decks)

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