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PHARM > Drug Disposition and Pharmacokinetics > Flashcards

Drug Disposition and Pharmacokinetics Flashcards

1
Q

Qualitative description of how the body handles the drug; includes how the drug is absorbed, where it is distributed, how it’s metabolized, and how it is eliminated in the body

A

Drug disposition

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2
Q

Quantitative description of drug disposition

A

Pharmacokinetics (PK)

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3
Q

Parameters that describe drug disposition

A

Absorption, distribution, metabolism, excretion (ADME)

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4
Q

Drug must be present at adequate concentration at its site of action to produce a pharmacological effect. (T/F)

A

True.

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5
Q

Route of administration and the conditions at the route of administration:

A

Absorption

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6
Q

Route influences extent and speed that drug is absorbed, thus influencing what?

A

The efficiency of therapeutic effect

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7
Q

Major site of oral drug absorption:

A

Intestine

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8
Q

Oral route of drug administration have what issues

?

A

slower rate of absorption and subject to LIVER FIRST-PASS METABOLISM

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9
Q

Bypasses first pass metabolism:

A

Parenteral (“beyond” the alimentary tract) - injection, inhalation, intranasal

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10
Q

Quicker absorption –>

A

quicker time to effect (intravenous, inhalation, sublingual, intramuscular, subcutaneous, rectal, oral, transdermal)

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11
Q

Fraction of the dose of unchanged drug that reaches systemic circulation by any route

A

Bioavailability

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12
Q

Drugs give by IV have bioavailability of what? Other routes will be what?

A

IV = 100%, other = <100%

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13
Q

For routes other than IV, bioavailability depends on:

A

Chemical form of drug, contact time with the absorbing surface, presence of drug metabolizing enzymes and efflux transporters can change or eliminate the drug before it reaches the systemic circulation

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14
Q

Drug has to ENTER circulation after administration:

A

Absorption

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15
Q

Drug has to traverse WITHIN the body:

A

Distribution

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16
Q

Drug has to move INTO liver and hepatocytes:

A

Metabolism

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17
Q

Drug/metabolites must be ELIMINATED:

A

Excretion

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18
Q

Mechanisms by which drugs are transported after administration:

A
  1. passive transfer

2. carrier-mediated transport

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19
Q

Passive transfer consists of:

A
  1. bulk flow (filtration)

2. passive diffusion

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20
Q

Carrier-mediated transfer consists of:

A
  1. facilitated diffusion
  2. active transport
  3. receptor-mediated endocytosis
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21
Q

Passage of compounds through intercellular pores:

A

Bulk Flow (peripheral capillaries and kidney)

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22
Q

Passage of drugs by dissolving into and diffusing across lipid membranes:

A

Passive Diffusion

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23
Q

What is the most important transport processes?

A

Passive diffusion; most drugs are targeted for the enteral route that utilizes passive diffusion as a primary mechanism for absorption.

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24
Q

Properties of molecules that cross by passive diffusion:

A
  1. uncharged, non-ionized

2. lipid soluble (lipophilic or hydrophobic)

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25
Q

Measured by the distribution in an immiscible mixture of an organic-aqueous solvent:

A

Lipophilicity

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26
Q

The greater the permeability, the greater the lipophilicity. (T/F)

A

True.

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27
Q

Diffusion of drug from a high to low gradient is known as which law?

A

Fick’s 1st law of diffusion

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28
Q

Most drugs are small molecular weight organic acids or bases that exist just as ionized forms. (T/F)

A

False. they exist in both ionized and non-ionized forms

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29
Q

Neutral molecule which can reversibly dissociate into an anion to yield a proton

A

Acidic Drug

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30
Q

Proton Donor

A

Acidic drug

31
Q

Neutral molecule which can form a cation by combining with a proton.

A

basic drug

32
Q

Proton acceptor

A

basic drug

33
Q

Difference between cation and anion:

A 
Cation = positively charged,
Anion = negatively charged
34
Q

Non-ionized form of drug passively diffuses. (T/F)

A

True. Diffuse until equal concentrations of uncharged are attained on both sides of membrane (equilibrium).

35
Q

Total amount of drug on either side of the membrane equals:

A

non-ionized + ionized forms

36
Q

Amount of non-ionic and ionic species depends on:

A
  1. whether the drug is an acid or base
  2. pKa of the drug
  3. pH of the environment
37
Q

Term used for pH where 50% is ionized and 50% is non-ionized:

A

pKa = percent ionization is 50%

38
Q

Accumulate at high pH side of membrane:

A

Weak acidic drugs (or bases)

39
Q

Accumulate at low pH side of membrane:

A

Weak basic drugs (or acids)

40
Q

For each pH unit from the pKa, it changes the N/I ratio by what?

A

10

41
Q

For a weak acid what happens as pH increases/decreases in regards to ionization?

A

pH increases for weak acid: favors ionized.

pH deceases for weak acid: favors non-ionized.

42
Q

For a weak base what happens as pH increases/decreases in regards to ionization?

A

pH decreases for weak base: favors ionized.

pH increases for weak base: favors non-ionized.

43
Q

Three examples of carrier-mediated transport:

A
  1. facilitated diffusion
  2. active transport
  3. receptor-mediated endocytosis
44
Q

Protein transporter moves drug DOWN a chemical/concentration gradient until equilibrium is achieved:

A

facilitated diffusion

45
Q

This type of diffusion is energy INDEPENDENT:

A

facilitated

46
Q

This type of diffusion is bi-vectorial; same protein can transport in both directions across the membrane but down the concentration gradient:

A

facilitated

47
Q

SLC =

A

solute carrier proteins, facilitated diffusion

48
Q

Transports drug AGAINST its concentration gradient (from lower to higher amount of drug).

A

Active transport

49
Q

This type of transport is energy DEPENDENT and uses what?

A

Active transport; uses ATP (requires energy to transport against its concentration gradient)

50
Q

Difference between primary and secondary transporters:

A

Primary: energy machinery contained within the transporter; ATP Binding Cassette, ATP as energy.
Secondary: energy source is provided from other sources not within the transporter; Solute Carrier

51
Q

OAT stands for:

A

Organic Anion Transporter

52
Q

OCT stands for:

A

Organic Cation Transporter

53
Q

3 examples of neurotransmitter re-uptake transporters:

A

NET, DAT, SERT (all are Na+ symporters)

54
Q

MDR stands for:

A

multi-drug resistance

55
Q

MRP stands for:

A

Multidrug resistance-associated proteins

56
Q

Selectivity is based on size, it is not saturable, and not energy dependent:

A

bulk flow (filtration)

57
Q

Selectivity is based on non-ionized/lipophilic, it is not saturable, and not energy dependent:

A

passive diffusion

58
Q

Has broad Selectivity, it is saturable, and not energy dependent:

A

Facilitated diffusion

59
Q

Has broad Selectivity, it is saturable, and is energy dependent:

A

active transport

60
Q

Highly ionized drugs (N/I <0.001) will not ever be absorbed to some extent. (T/F)

A

False, they will eventually be absorbed to some extent.

61
Q

Equilibrium os non-ionic species is never attained where?

A

In the gut/GI tract

62
Q

6 factors that determine rate and extend of drug distribution:

A
  1. blood flow and tissue mass/volume
  2. capillary permeability
  3. lipid solubility of the drug
  4. extend of drug ionization and tissue pH
  5. transport mechanisms available
  6. extent of drug binding to proteins
63
Q

In regards to tissue vascularization, give examples of high equilibrate that happens quick and first compared to poor equilibrate that occurs slowly:

A

Highly equilibrate quicker and first: liver and brain
Intermediate: muscle, skin
Poorly equilibrate very slowly: adipose, bone

64
Q

What occurs when the concentration of charged species is higher in tissue than in plasma and the drug accumulates in tissue?

A

Ion trapping

65
Q

Compounds that are charged at all physiological pHs diffuse poorly across lipid membranes and rely on carrier-mediated transport to cross membranes. (T/F)

A

True.

66
Q

Which would provide the fastest, greatest distribution of drug?

A

Bulk flow.

67
Q

Equation for Apparent volume of distribution (Vd) =

A

Vd (L) = X0 (mg) / Cp (mg/L); the amount of drug in body/the concentration of drug in the plasma immediately after IV administration.

68
Q

Volume of distribution and concentration of drug in plasma are inversely related. what does this mean?

A

If concentration decreases, then volume of distribution increases; if concentration of drug in plasma increases, then volume of distribution decreases

69
Q

The volume that X0 occupies in body to yield Cp is known as:

A

Apparent volume of distribution (Vd).

70
Q

What is the volume of fluid for the following: plasma, extracellular fluid, total body water?

A

plasma: 3 L, extracellular fluid: 12 L, total body water: 42 L.

71
Q

If Vd > 100, what does can we assume this means?

A

volume of distribution is considered stored in fat.

72
Q

What is the significance of volume of distribution?

A

utilized in the calculation of doses and dose rates

73
Q

Compare larger Vd to smaller Vd.

A

Larger Vd = more lipophilic, easier to cross BBB, accumulate in tissues or fat, maintained longer in body, typically require hepatic metabolism for elimination;
Smaller Vd = more hydrophilic, more rains in the blood with little accumulation in fat, tissue or brain, may be large MW or bind to plasma proteins, eliminated primarily in kidney

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