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Pharmacology > Pharmacokinetics > Flashcards

Pharmacokinetics Flashcards

1
Q

pharmacokinetics

A

what happens to a drug when you put it in your body (effect of body on drug)

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2
Q

What does the drugs concentration in the body depend on

A

drug regimen (dose, route, formulation, frequency)
how the drug moves through the body over time (ADME)

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3
Q

What does pharmacokinetics describe

A

ADME

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4
Q

What is on the X axis of a PK curve

A

Time

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5
Q

what is on the Y axis of a PK curve

A

Blood level or “plasma concentration”

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6
Q

Pharmacodynamics = __________ = what the drug does to the body

A

concentration-effect relationship

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7
Q

Pharmacokinetics = ____________ = What the body does to the drug

A

Dose-Time-Concentration relationship

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8
Q

codeine getting metabolized (broken down) by hte body into a few different compounds, including morphine.

A

Pharmacokinetics

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9
Q

Opioids, such as codeine and morphine, work by agonizing (activating) mu-opioid receptors in the central nervous system causing analgesia.

A

pharmacodynamics

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10
Q

a central goal of drug therapy is to _____

A

achieve a desired effect while inflicting the minimum possible adverse effects

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11
Q

Understanding PK allows us to find the drug dosing regimen necessary to achieve the least possible adverse effects. This is achieved by __________

A

getting a drugs blood level in the Theraputic window

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12
Q

what is the theraputic window

A

the window between the minimum theraputic dose and the dose where the drug becomes toxic

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13
Q

what does Enteral mean

A

goes through the intestine (digestive tract)

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14
Q

what does parenteral mean

A

Stays outside digestive tract

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15
Q

why does a 150mcg tablet taken orally and 75mcg given IV have the same effectiveness

A

IV is absorbed better than oral

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16
Q

Bioavailability (F)

A

the Fraction of intact drug that reaches the systemic circulation

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17
Q

F= _____ for IV drugs

A

100%

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18
Q

if you take 100mg of a drug and only 80% of the drug reaches the systemic circulation (bloodstream) what is F? (what is bioavailability)

A

F=80%

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19
Q

What is used to measure bioavailability

A

Area Under the Curve (AUC)

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20
Q

What does AUC represent

A

bioavailability, the total systemic exposure to a drug.

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21
Q

What is the blue line, what is he green line

A

blue line = IV
green line = oral

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22
Q

Which of the PK curves below shows the BEST (highest) bioavailability

A

the one with the red

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23
Q

What are two things that reduce bioavailability

A

incomplete amount of absorption
the First pass effect

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24
Q

what is the first pass effect

A

when the concentration of a drug is greatly reduced before reaching circulation

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25
Q

Paracellular transport

A

it can go around cells (through the junctions between cells)

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26
Q

facilitated diffusion

A

it can get trasnported along a concentration gradient

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27
Q

diffusion

A

it can diffuse through the cells (ie throught the lipid bilayer cell membranes)

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28
Q

In general, drugs that are good at diffusing through lipid bilayers are:

A

small molecules
lipophilic
uncharged

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29
Q

Which molecule would be better at crossing through cell layers

A

Fentanyl (left) because its smaller than vncomyocin (right)

30
Q

This tissue cares alot about size, charge, and lipophilicity of drugs that pass through it

A

continuous capillaries such as CNS (blood brain barrier), skin and lungs.

31
Q

This tissue cares a little bit about size, charge, and lipophilicity of drugs that pass through it

A

fenestrated capillaries such as (kidneys and small intestine)

32
Q

this tissue cares the least about size, charge, and lipophilicity of drugs that pass through.

A

sinusoidal capillaries (liver, lymph nodes)

33
Q

influx transporters

A

active transport proteins that move drugs into cells

34
Q

efflux transporters

A

active transport proteins that move drugs out of cells

35
Q

active transport

A

transport requiring energy

36
Q

What is a significant active trasnporter in PK and what is its job

A

efflux transporters
job is to keep xenobiotics (drugs) out of certain places.

example: p-gp is an important efflux transporter that keeps many drugs in the intestine and out of the brain

37
Q

What is an example of p-gp

A

benadryl and allegra

benadryl is 1st generation antihistamine (drowsy)

Allegra is 2nd generation antihistamines (non drowsy)

this works because allegra has gp-gp transporters that keep the allergy medicine in the systemic circulation but out of the CNS

38
Q

blocking histamine receptors peripherally helps_______ but blocking histamine receptors in the CNS causes ______

A

blocking histamine receptors peripherally helps allergies but blocking histamine receptors in the CNS causes drowsiness

39
Q

What are the additional considerations when considering the absoprtion of tablets/capsules

A

dissolution of the drug from tablet or capsule form
stability of drug
rate of gastric emptying
intestinal motility and drug interactions

40
Q

dissolution of the drug from tablet or capsule form includes

A

that the drug must be in solution to be absorbed and different formulations dissolve at different rates

41
Q

What does rate of gastric emptying entail

A

absorption is much faster in the small intestine (more surface area, more permeability, more blood flow)
the speed of getting to small iintestine limits the sped of the drug getting absorbed
food slows gastric emptying

42
Q

what does inestinal motility and drug interactions entail

A

pH, surface area, permeability, and efflux transporter density
drugs may bind to other contents of the intestine which can prevent absorption

43
Q

What are the 2 possible pathways that drugs given by IM/SQ/ID can enter the systemic circulation

A

diffusion through capillary membranes
getting carried through the lymph system

44
Q

the pathway consisting of diffusion through capillary membrane is forgiving of ____ and not forgiving of ____

A

very forgiving of polarity and charge
less forgiving of size

45
Q

the pathway of getting carried through the lymph system, name 4 facts about this pathway

A
  1. lymph system is the body’s “garbage collector”
  2. large molecules and proteins tend to go this route
  3. lymph system moves very slowly - which makes absorption slow
  4. enzymatic breakdown of drugs can occur in lymph nodes
46
Q

Speed of absorption when given IM/SQ/ID is affected by

A

slow moving systems
site of injection
local bloodflow
temperature
rubbing at injection site

47
Q

Vancomyocin ( a large hydrophilic molecule) would be be absorbed which route and why

A

IV because the large molecule = hard to absorb and hydrophillic = good diffusion through capillary walls

48
Q

Once any drug reaches the systemic circulation, it gets carried through the _____________, a major site of metabolism

A

liver

49
Q

What is the key difference between enteral and parenteral that has to do with passing through the liver

A

enteral drugs go through the liver before they reach the systemic circulation via the hepatic portal vein

50
Q

Aside from first pass (getting metabolized by the liver first) what are three other hazards along the way for enteric drugs

A
  1. not getting absorbed into the gut wall (exretion into feces)
  2. breakdown (metabolism) by the gut wall
  3. excretion into bile by liver
51
Q

Once a drug gets to the systemic circulation, it starts (reversibly)____________________

A

Once a drug gets to the systemic circulation, it starts (reversibly) distributing itself to different body tissues (extravascular space)

52
Q

Where the drug distributes to in the body depends on:

A
  1. how well it diffuses through different membranes (size lipophilicity, charge)
  2. what it likes to bind to (proteins in the plasma or other tissues)
53
Q

protein bound drugs

A

drugs that bind heavily to plasma proteins and cannot diffuse through membranes

54
Q

unbound or free drugs

A

the only type of drug that can leave the bloodstream (or be active)

55
Q

some drugs have a particular affinity for certain _________. give an example

A

tissues
bisphosphonates (osteoporosis drugs) have high affinity for bone minerals

56
Q

What is the formula for volume of distribution and what does it represent

A

represents how the drug gets distributed by finding whether the drug stays mostly in the bloodstream or if it enters other tissues

Volume of distribution = total amount of drug in body(mg)/plasma concentration of drug (mg/L)

57
Q

If the drug stays in the bloodstream what will the volume distribution be

A

close to the volume of the blood

58
Q

If the drug diistributes widely around the body, what will the Volume of distribution (Vd) be

A

very large.

59
Q

The Vd is an “_________”

A

imaginary volume
go back and listen to slide 33

60
Q

Go back and do checkpoints 7,8,9

A
61
Q

metabolism is also known as

A

biotransformation

62
Q

what happens during metabolism/biotransformation

A

a parent drug is converted to a metabolite, which is a different chemical form that is more readily excreted from the body

63
Q

metabolites can be

A

active or inactive

for example, morphine has both active and inactive metabolites

64
Q

prodrugs

A

druugs that have inactive parent forms and active metabolites

such as plavix (clopidogrel)

65
Q

Metabolism is performed by ________ which are present in tissues all over the body, but the ______ is the most important site of metabolism

A

enzymes, liver

66
Q

Phase one metabolism includes

A

oxidation, reduction, or hydrolysis

67
Q

phase two metabolism includes

A

conjugation, acetylation and methylation

68
Q

some drugs such as hydrophobic drugs go through ________ while others such as hydrophillic drugs _______

A

some drugs such as hydrophobic drugs go through the phases sequentially (some just do one, or two, some do both) while others such as hydrophillic drugs leave the body before gettting metabolized at all

69
Q

loves lipids—> _________
loves water —-> _________

A

loves lipids—> liver
loves water —-> urine

70
Q

stopped at slide 40

A

ok

Pharmacology (19 decks)

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