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Nu 578: Ch 4-19 Exam 1 > Chapter 4 - Pharmacokinetics > Flashcards

Chapter 4 - Pharmacokinetics Flashcards

1
Q

Define Pharmacokinetics

A

Study of drug movement thoroughout the body

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2
Q

What are the 4 phases of pharmacokinetics?

A

Absorption, Distribution, metabolism and excretion.

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3
Q

Absorption

A

Movement of a drug from its site of administration into the blood(circulation)

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4
Q

The most common mechanism for drug absorption is

A

PASSIVE DIFFUSION

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5
Q

Distribution

A

Drug movement form the blood to the interstitial space of tissues and from there into cells

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6
Q

Metabolism

A

enzymatically mediated alteration of drug structure.

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7
Q

Excretion

A

movement of the drugs and their metabolites out of the body

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8
Q

The combination of metabolism and excretion is known as_____?

A

elimination.

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9
Q

The intensity of the response of a drug is directly related to the ________ of the drug at its site of action.

A

concentration

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10
Q

What is the major barrier to passage through a cell?

A

the cytoplasmic membrane (Membrane that surrounds the cell)

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11
Q

What are phospholipids?

A

fats that contain an atom of phosphate

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12
Q

What are the three ways for a drug to cross the cell membrane?

A
  1. Passage through channels or pores
  2. Passage with the aid of a transport system
  3. direct penetration of the membrane.
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13
Q

The most common way a drug crosses the membrane is by _______.

A

direct penetration

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14
Q

Which compounds are likely to cross membranes via channels.

A

small ions such as potassium and sodium.

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15
Q

What are transport systems?

A

carriers that can move drugs from one side of the cell membrane to the other.

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16
Q

what is P-gylcoprotein?

A

transmembrane protein that transports a wide variety of drugs OUT of the cell

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17
Q

P-gylcoprotein transports drugs into the ________ for elimination.

A

Bile

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18
Q

In the placenta p-gylcprotein transports drugs back into the _________, therby _____ fetal drug exposure

A

maternal blood; reducing

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19
Q

What is a polar molecule?

A

molecules with an uneven distribution of electrical charge.

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20
Q

What drug is an example of a polar drug?

A

Gentimicin

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21
Q

What is an ion?

A

molecules that bear a net charge

They are unable to cross membranes

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22
Q

What is a quanternary ammonium compound?

A

molecules containing at least one atom of nitrogen and carry a positive charge at all times

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23
Q

What is an Acid?

A

a compound that can give up a hydrogen ion (proton donor)

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24
Q

What is a base?

A

a compound that can take up a hydrogen ion (Proton acceptor)

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25
Q

explain ion trapping

ph partitoning

A

process whereby a drug accumulates on teh side of a membrane where the pH most favors its ionization.

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26
Q

What factors affect drug absorption?

A 
Rate of dissolution
Lipid solubility
Surface Area
Blood Flow
Ph partitioning
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27
Q

The larger the surface are the ______ the absorption will be.

A

faster

for this reason, a lot of drugs are usually absorbed in the small intestines

28
Q

What type of insulin is safe for IV infusion

A

Regular insulin. It is a clear liquid

29
Q

What type of insulin can only be given SQ

A

NPH. Fatal if given IV

30
Q

What would happen if concentrated EPI was given IV

A

overstimulate the heart and blood vessels, causing severe hypertension, cerebral hemorrhage, stroke and death

31
Q

When a drug is administered IM _____ is the only barrier to absorption

A

capillary wall

32
Q

What is the major barrier to absorption in the GI tract?

A

The GI epithelium (drugs must pass through these cells rather than between them).

33
Q

Enteric- coated preparations are covered wit a material designed to dissolve in the ____.

A

Intestine (not in the stomach)

34
Q

Define distribution

A

movement of drugs throughout the body

35
Q

Drug distribution is determent by what three factors?

A
  1. blood flow to tissues
  2. ability of drug to exit vasuclar system
  3. ability of a drug to enter cells
36
Q

Why cant abscess be effectively treated with ABX if they are not drained?

A

because abscesses have no blood supply. Infection bust be drained before ABX will work

37
Q

What drugs are able to pass through the blood brain barrier?

A

Lipid soluble drugs and drugs with a transport system.

38
Q

Most drug metabolism takes place in the _____

A

Liver

39
Q

Drugs metabolised in the liver do so by what system?

A

P450 system ( hepatic microsomal enzyme system)

40
Q

What does cytochrome P450 consist of?

A

12 closely related enzyme families — Three important ones are CYP 1,2 and 3

41
Q

What does CYP 1, CYP2, and CYP3 do?

A

They metabolize drugs - The other 9 metabolize endogenous compounds (steroids, fatty acids)

42
Q

What is a prodrug?

A

a compound that is inactive at administration and the undergoes conversion its active form via metabolism.

43
Q

At what age does the liver develop to its full capacity?

A

1 year of age. Therefore of the drug is , the metabolizing capacity is decreased. This also happens in the elder - may need to REDUCE drug doses

44
Q

What is a substrate?

A

drugs that are metabolzied by P450 enzyme

45
Q

What is an inducer?

A

Drugs that act on the liver to increase rates of drug metabolism.

46
Q

What is induction?

A

Process of stimulating enzyme synthesis

47
Q

What happens when a drug is an inducer and a substrate?

A

The drug can increase the rate of its own metolism, thereby necessitating an increase its own dosage to maintain therapeutic effects.

48
Q

What is an inhibitor?

A

Drugs that act on the liver to decrease rates of drug metabolism. Process is known as inhibition.

49
Q

How do inhibitors provide therapeutic consequences?

A

bc slower metabolism can cause an increase in active drug accumulation. This can lead to an increase in adverse effects and toxicity.

50
Q

What is first pass effect?

A

rapid hepatic inactivation of certain oral drugs. The capacity of the liver to metabolize a drug is extremely high and that drug can be completely inactivated on its first pass through the liver. As a result no therapeutic effects can occur.

51
Q

Name a drug that undergoes first pass effect

A

nitrocylcerin — so it is given SL

52
Q

What is enerohepatic recirculation?

A

repeating cycle in which a drug is transported from the liver into the duodenum/intestine (via the bile duct) then undergoes reabsorption back to the liver(portal blood). — this can prolong a drugs sojourn in the body.

53
Q

What is glucuronidation?

A

is the addition of glucuronic acid to a substrate —– example: process in which a hydrophilic glucose (glucuronic acid) derivative is attached to phenytonin. As a result phenytoin is rendered much more water soluble and can be rapidly excreted by the kidneys.

54
Q

What drugs are most affected by enterohepatic re-circulation?

A

Drugs that have undergone glucuronidation.

55
Q

Urinary excretion is the net result of what three processes?

A
  1. Glomerular filtration
  2. passive tubular reabsorption
  3. Active tubular secretion
56
Q

Passive tubular renal absorption is limited to_______

A

Lipid soluble compounds

57
Q

Competition for transport has been employed clinically to _______ the effects of drugs that normally undergo rapid renal excretion

A

Prolong

58
Q

What is an example of competition for transport

A

Penicillin —– when administered some, penicillin is rapidly cleared from the body by active tubular transport — excretion of Penicillin can be delayed by concurrent ministration of probenecid an agent that is removed from the blood by the same tubular transport system that pumps penicillin

59
Q

Penicillin can be delayed by concurrent administration of ______

A

Probenecid

60
Q

Drug levels ________ as the medication undergoes absorption.

A

Rise

61
Q

Drug levels ______ during metabolism and excretion

A

Decline

62
Q

The duration of effects on a drug is determined largely by the combination of _______ and ________

A

Metabolism and excretion

63
Q

Define half life

A

The time required for the amount of drug in the body to decreased by 50%

64
Q

What is the half-life of morphine?

A

Three hours

65
Q

The _______ determines the dosing interval of a drug

A

Half-life

66
Q

How many half lives does it take to reach a plateau?

A

About 4.

Nu 578: Ch 4-19 Exam 1 (12 decks)

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