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Pharmocology > Lehne Book: Chapter 4 - Pharmacokinetics > Flashcards

Lehne Book: Chapter 4 - Pharmacokinetics Flashcards

1
Q

Pharmacokinetics is made from two greek words Pharmakon and Kinesis…what do these words mean?

A 
pharmakon = poison/drug
kinesis = motion
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2
Q

What are the four basic pharmacokinetic processes? Hint: MOTION

Acronym: MADE

A
  1. absorption
  2. distribution
  3. metabolism
  4. excretion
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3
Q

MEtabolism + excretion = ___________

A

elimination

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4
Q

The movement of a drug from its site of administration into the blood?

A

absorption

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5
Q

Drug movement from the blood to the interstitial space of tissues and from there into cells (from blood to target)

A

distribution

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6
Q

AKA Biotransformation; enzymatically mediated alteration of drug structure.

A

Metabolism

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7
Q

Movement of drugs and their metabolites out of the body.

A

excretion.

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8
Q

What are the three ways a a drug can cross cell membranes?

A
  1. passage through channels or pores
  2. passage with aid of transport system
  3. direct penetration of the membrane itself.
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9
Q

In order to directly penetrate membranes, a drug must be ______ ______ .

A

Lipid Soluble (lipophilic) p.28

Remember: Like dissolves like. If chemical is lipid soluble it can get through lipid membrane

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10
Q

T or F: Polar molecules and ions are lipid soluble.

A

False, they are not lipid soluble and cannot pentrate the membrane

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11
Q

______ molecules are molecules with uneven distribution of electrical charge. They have no net charge.

A

Polar

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12
Q

Molecules that do bear a net charge, and unless extremely small, cannot cross the cell membrane are called?

A

ions

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13
Q

Whether a weak acid or base carries a charge is determined by the __ of the surrounding medium.

A

pH

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14
Q

An acid _____ a proton (hydrogen ion). A base _____a proton (hydrogen ion). What is the name of the process when this happens?

A

acid donates; base accepts

process is called ionization

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15
Q

T or F: Acidic drugs such as aspirin ionize in the stomach.

A

False, Acid ionizes in base. It does not ionize in acid, as in the stomach. It can pass through membranes of the stomach because it has not ionized. Once it hits the basic environment of the intestine, it can no longer pass through the membrane.

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16
Q

The ____ of absorption is how soon effects will begin. The _____ of absorption helps determine how intense effects will be.

A

Rate;

amount

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17
Q

Rate of dissolution, surface area, blood flow, lipid solubility and pH partitioning are all factors affecting _______.

A

absorption

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18
Q

The two common routes of drug administration are:

A

enteral and parenteral.

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19
Q

What is the difference between enteral and parenteral?

A

enteral is in the GI Tract. Parenteral is anywhere else. Usually means by IV,IM, SC.

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20
Q

Why does the site of drug administration matter? How does it change the effects?

A

The barriers to absorption associated with each route are different.

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21
Q

Does absorption take place when IV drugs are administered?

A

No. Absorption is the movement from site of administration INTO the blood. WIth IV, it goes directly into the blood.

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22
Q

What is the advantage to using IV for poorly soluble drugs?

A

The drugs can be dissolved in large volume of fluid and into the body through IV.

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23
Q

What is the recommended time for injecting a drug via IV? Why?

A

Over a 1 minute interval at least. It takes 15 second from arm to brain. We would have the chance to see any negative effects before emptying a syringe into the patient. p.33

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24
Q

What should you check for in IV solutions before administering drugs?

A

Check that drugs are in solution. If cloudy or contains particles, do not use!!!

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25
Q

What is the only barrier to absorption for IM administration?

A

the capillary wall; The same goes for SC (or SubQ)

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26
Q

What determines the absorption rate of IM administration?

A
  1. water solubility

2. blood flow at the site of injection.

27
Q

If a drug is has poor solubility, even in IV solution, what method of administration can we use?

A

IM

28
Q

What is a depot injection?

A

the administration of a sustained-action drug formulation that allows slow release and gradual absorption, so that the active agent can act for much longer periods than is possible with standard injections. Depot injections are usually given deep into a muscle.

29
Q

What is a benefit to an IM Depot injection?

A

Long lasting means fewer injections

30
Q

If your patient is on coumadin, warfarin or any other anticoagulant, can you give them IM medications?

A

No. The risk of bleeding is too high.

31
Q

What are two barriers to absorption in the case of oral administration?

A
  1. GI Tract epithelial cells

2. Capillary Wall

32
Q

The rate and extent of drug absorption following oral admistration can be highly variable due to:

  1. solubility and stability of drug
  2. gastric and intenstinal pH
  3. gastric emptying time
  4. _____________________
  5. other drugs in system
  6. coatings on the drug itself
A

Food in the gut.

33
Q

What is the safest administration?

A

oral, no risk of fluid overload, infection or embolism, reversible.

34
Q

A ______ is a mixture of a drug plus binders and fillers, all of which have been compressed together.

A

tablet

35
Q

An ________-________preparation is covered with material designed to dissolve in the intestine, but not the stomach. Those materials used in the covering include fatty acids, waces and shellac.

A

Enteric-Coated

36
Q

________ - _________ preparations are capsules filled with tiny spheres which contain the actual drug. The spheres have their own coatings. Why?

A

Sustained-Release; because the coatings dissolve at different times, allowing the drug to be released over time.

37
Q

Drug distribution (movement of drugs throughout the body via the blood) is determined by three major factors:

A
  1. blood flow to tissues
  2. ability of drug to exit vascular system
  3. ability to enter cells
38
Q

Why are abscesses and tumors resistant to drug therapy?

A

no blood supply in abscess

limited blood supply in tumor

39
Q

Drugs enter into the blood and are transported where to exit the vascular system?

A

Capillary beds

40
Q

Only drugs that are _____ ______ or have a _______ _____ can cross the BBB.

A

lipid soluble ; transport system

41
Q

what protein in the blood binds to free drugs in the bloodstream?

A

plasma albumin

42
Q

T or F: Hepatic metabolism always results in the breakdown of drugs into smaller molecules.

A

False, sometimes is synthesizes a molecule larger than the parent drug.

43
Q

Drugs must be converted from ______-soluble to _______-soluble so that they may be excreted from kidneys. The most important consequence of drug metabolism is promotion of renal drug excretion.

A

lipid;water

44
Q

A drug that is pharmacologically inactive as administered, but becomes active in the body after conversion.

A

Prodrug (p.39)

….like provirus…sits around and waits.

45
Q

List some reasons children under 1 are at risk with medication…

A
  1. BBB not fully developed
  2. liver not fully developed
  3. Kidneys are not full developed.
46
Q

_______ is the process of stimulating enzyme synthesis.

A

induction p.39

47
Q

How can malnutrition effect hepatic-drug metabolism?

A

poor diet may be missing important cofactors required for the drug to metabolize/function.p.40

48
Q

The most important organ for drug excretion is the ______.

A

kidney

49
Q

What are the three steps in renal drug excretion?

A

http://www.youtube.com/watch?v=4X8pAizadWI

  1. glomerular filtration (moves drugs from blood to urine)
  2. passive tubular reabsorption (lipid soluble drugs move into blood)
  3. active tubular secretion (tubular pumps organic acid /base from blood to urine)
50
Q

What are some examples of nonrenal routes of drug excretion?

A
  1. Breast milk
  2. Bile (bile goes to small intestine, then our through feces)
  3. Lungs (anesthetics)
  4. Sweat and Saliva (in small amts)
51
Q

If we administer two drugs that use the same transport system, will excretion of them be delayed? if so, why?

A

Yes, because the renal tubules are like revolving doors and can only carry a limited number of drug molecules per unit of time.

52
Q

T or F: There is a direct correlation between therapeutic and toxic responses and the amount of drug present in plasma.

A

True. We can measure concentration in plasma instead of at the site (ie. can’t take sample from epileptic brain).

p.43

53
Q

Two plasma drug levels are super important: 1. minimum effective concentration; 2.____________

A

toxic concentration

54
Q

T or F: Concentration of drug must be at or above MEC.

A

True

55
Q

The _______ range is between the MEC and the toxic concentration.

A

Therapeutic Range

56
Q

Which drug is harder to administer, one with a broad or narrow therapeutic range?

A

narrow. broad has more room to move within the range.

57
Q

_________ is defined as the time required for the amount of drug in the body to decrease by 50%

A

Drug Half-Life

58
Q

When the amount of drug eliminated between doses equals dose administered, average drug levels will remain constant and __________ is reached.

A

Plateau

59
Q

T or F: Regardless of the size of the dose, reaching the plateau takes the same amount of time for that particular drug.

A

True. The grams in the body would be greater, but the time it takes would not be different since it is always based on half-life.

60
Q

Fluctuations are seen between doses. The high concentration is called peak. The low concentration is the trough. How can we reduce fluctuations in drug levels?

A
  1. Administer by continuous infusion
  2. Administer depot preparation
  3. reduce the size of each dose and the dosing interval simultaneously.
61
Q

The longer the half-life, the longer it takes to plateau. What can be done to reach the initial high level quicker upfront?

A

Administer a loading dose. By definition it is a large initial dose. p. 45

62
Q

After the loading dose, _______ doses are given.

A

maintenance

63
Q

T or F: It takes four half-lives for a drug to clear the body.

A

True. Each drug has it’s own individual half-life (length of time). It will take four of those to clear the system.

Pharmocology (22 decks)

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