Clinical Pharmacology I - Pharmokinetics Flashcards

1
Q

What is the standard definition of pharmacokinetics?

A

What the BODY does to the DRUG

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2
Q

What is the standard definition of pharmacodynamics?

A

What the DRUG does to the BODY

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3
Q

Which two processes do you need to take into account to determine the amount of drugs that a person uses?

A

Pharmacokinetics and pharmacodynamics

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4
Q

What does ADME mean?

A

A: Absorption
D: Distribution
M: Metabolism
E: Elimination

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5
Q

What is meant with absorption?

A

Intake into the body

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6
Q

What is meant with distribution?

A

Division/partition throughout the body

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7
Q

What is meant with metabolism?

A

Conversion in the body

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8
Q

What is meant with elimination?

A

Excretion from the body via urine, bile and feces

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9
Q

How much of the medication that is administered via IV is taken up by the body?

A

100%

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10
Q

Which two factors do you have to take into account when you determine the amount of oral medication that is taken up by the body?

A
  • How much of the medicine is absorbed?
  • Form of the medicine (delayed-release, enteric-coating, etc.)
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11
Q

How do you accomplish delayed-release?

A

Equip the pill with coating to ensure that the gastric acid can’t get through –> drug intact when it reaches the intestine

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12
Q

When are oral dosage forms not useful?

A

During intensive care and/or after surgery

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13
Q

Why is oral dosage not useful during intensive care and/or after surgery?

A

The stomach and intestine are often delayed or functionally immobile

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14
Q

What is the definition of bioavailability?

A

The fraction of an administered dose of unchanged drug that reaches the systemic circulation

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15
Q

What is the term for bioavailability?

A

F or BB

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16
Q

What is the F of metoprolol and what does that mean?

A

30-70%. This means that this percentage of the administered dose reaches the systemic circulation.

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17
Q

Why does the F value not correspond to the dose of oral?

A
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18
Q

Tobramycin has a low F value. Why would you take this orally?

A
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19
Q

Which kind of administration is the most easy to give and why?

A

IV. Absorbed instantly

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20
Q

What is the order of administration routes? (fast to slow)

A
  • Intravenous (IV)
  • Intramuscular
  • Subcutaneous
  • Oral
  • Rectal
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21
Q

How does medication spread through the body? (4)

A
  • Hydrophilic tissues: blood and muscles
  • Lipophilic tissues: dermis, nerves and fat tissues
  • Brain: blood-brain barrier
  • Placenta/breastmilk
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22
Q

Which formula’s can you use for the volume of distribution?

A
  • Vd = Ab/C
  • Vd = F x Dose / plasma concentration
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23
Q

What do Ab and C mean?

A

Ab = quantity of drug in the body system
C = concentration in the blood

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24
Q

Which substances have a high Vd and why?

A

Lipophilic substances, because they distribute to the fat

25
Q

Which substances have a small Vd and why?

A

Hydrophilic substances, because they distribute to the water

26
Q

What are the fluid compartments in the body?

A
  • Intracellular fluid (within cells)
  • Extracellular fluid (outside cells)
  • Interstitial fluid (surrounding cells)
  • Plasma (blood)
27
Q

How can you give an unborn baby medication?

A

Low-dose for the mother

28
Q

What happens to the Vd when using drugs that diffuse to the intracellular fluid?

A

The Vd is equal to the total body water

29
Q

What happens to the Vd when using drugs that bind strongly to the tissue?

A

The Vd is higher than the total body water

30
Q

Name examples of drugs that diffuse to the intracellular fluid (2)

A
  • Ethanol
  • Benzylpenicilin
31
Q

Name examples of drugs that bind strongly to the tissue (3)

A
  • Fentanyl
  • Propofol
  • Digoxin
32
Q

Iets met body composition differences

A
33
Q

What is biotransformation?

A

Metabolism: chemical conversion in the body

34
Q

Which substances are created during biotransformation?

A

Metabolites (active OR inactive)

35
Q

Where does most of the conversion happen in the body and which enzymes are needed?

A

In the liver via the cytochrome P450 system

36
Q

Why do certain drugs need to be metabolized in the liver?

A

Most drugs are lipophilic. The drug must be converted to a water soluble form to be excreted by the kidneys

37
Q

What can change the “normal” breakdown of a drug? (2)

A
  • Genetic polymorphisms
  • Drug-drug interactions
38
Q

True or false: “Slow metabolizers generally don’t really have side-effects”

A

False. Slow metabolizers generally suffer from more severe side-effects

39
Q

To what is codeine metabolized in the liver and which enzyme is responsible for this conversion?

A

Morphine. CYP2D6

40
Q

What can be said about the effect of codeine for the different metabolizer types?

A
  • UR: high [morphine], increased effect
  • NM: average [morphine], normal effect
  • SM: low [morphine], decreased effect
41
Q

What happened to the baby that died when the mother took codeine?

A
  • Mother was an ultra-rapid metabolizer
  • Biotransformation by CYP2D6 to morphine
  • Over-dose of morphine reached the baby
42
Q

How can a high blood concentration of codeine that has been adminstered to the mother cause morphine intoxication of a baby?

A
  • Directly into fetus via placenta
  • Breastmilk
43
Q

What will be drawn up when you don’t respond to a drug as expected?

A

Pharmacokinetic profile

44
Q

When are dose adjustments necessary when drugs are primarily eliminated via the urine?

A

If a patient suffers from renal dysfunction

45
Q

Why are pharmacokinetics important?

A

To investigate and predict reactions to medicines

46
Q

What is meant with ‘intra-patient’?

A

One person reacts differently to the same medication in multiple or repeated dosings

47
Q

What is meant with ‘inter-patient’?

A

Differences between a group in how individuals react to a medication

48
Q

Which parameters play a role in onset?

A
  • C max: maximum concentration
  • T max: time when the maximum blood concentration is reached
49
Q

Which parameter plays a role in duration?

A

Cl: clearance. Elimination out of the body

50
Q

What is clearance?

A

The volume of plasma cleared of the drug per unit time (liter/hour)

51
Q

Which parameter plays a role in half-life?

A

T1/2: time necessary to decrease the blood concentration of a medication by 50%

52
Q

How can the half-life be prolonged?

A
  • Renal impairment
  • Intoxication
53
Q

What is the general rule for when the medication should be out of the blood?

A

4-5x T1/2

54
Q

When is a level steady?

A

3-5x T1/2

55
Q

Which parameter covers the exposure to the drug?

A

AUC = area under the curve when plasma drug concentration is plotted vs time

56
Q

Which parameters go up when clearance is decreased?

A
  • Half-life
  • AUC
57
Q

What is a pitfall if you give antibiotics to someone on the sub-therapeutic level?

A

Antibiotic resistance

58
Q
A